Scienfciflq  and  Medical 
Books,  aiii?an  objects 
of  Natural  History. 

A:,,®' rOOTE,  M D. 

122.J  Belmont  Ave.. 
Philadelphia,  Pa. 


FRANKLIN  INSTITUTE  LIBRARY 

PHILADELPHIA 

CIass..G  Book  .Z4.?.r  Accession . . C ^ _3 

Given  by „ . t € ...td.r..  1 


Digitized  by  the  Internet  Archive 
in  2015 


https://archive.org/details/handbookonsilexeOOfeuc 


A 


HAND-BOOK  ON  SILEX, 

EMBRACED  IN 

THREE  PRACTICAL  TREATISES  : 

I.  OF  SOLUBLE  GLASS, 

AND  ALL  ITS  APPLICATIONS  IN  THE  ARTS. 

II.  ON  GLASS  MAKING, 

IN  ALL  ITS  DETAILS. 

III.  A GUIDE  FOR  SOAP  MAKING, 

THE  MANUFACTURE  OP  ALL  SOAPS  iiljD  THEII?  MA^HUTHATIOUSi  ^ ^ ^ ^ " 


CONTAINING  ’ 


Thousands  of  Formulae  f^r  Wood  und’  Timpdr  Fire  'aid  Set  Iroof,  Silicifying 

Stones,  Mortars-  Cotorete^aai  Dydr^llc*  Lime,’  Wliito  Washes^  Paints  and 
Cements,  and  how  to  Proteot  Wooden  Shingles,  Pavements, 

Eail-Eoad  Sleepers,  &o.,  &c. 

By  Dr.  LEWIS  FEUCHTW ANGER, 

CHEMIST  AND  MINERALOGIST. 


PUBLISHED  BY  L.  & J.  W.  FEUCHTW  ANGER, 
No.  55  Cedar  Street. 


1871. 


Entered  according  to  Act  of  Congress,  in  the  year  eighteen  hundred  and 
seventy-one*, 


BY  Dr.  lewis  FEUCHTWANGER, 

‘ ^ ' o ® •Ii>th€«ofiice.o/.th^  ybfjtrian  of  Congress,  at  Washingtop,  ^ 


JOHN  W.  AMEBMAN,  PRINTER 
No.  47  Cedar  Street,  N.  Y. 


H^TRODUCTORY. 


The  first  edition  of  the  “ Practical  Treatise  on  Soluble 
Glass”  being  entirely  exhausted,  and  the  demand  for  the 
same  daily  increasing,  have  obliged  the  author  to  issue  a 
new  book,  under  the  name  of  “ A Hand-book  on  Silex,” 
wliich  is  to  embrace  three  separate  treatises  : 1.  That  on 
Soluble  Glass ^ with  all  the  latest  applications  in  the  arts, 
and  for  wood  and  stone.  2.  The  art  of  glass  making  in 
all  its  details.  3.  The  soap  maker’s  guide  for  the  pro- 
duction of  soaps  of  every  grade,  such  as  family,  toilet 
and  silicated.  The  Author  has  bestowed  particular  atten- 
tion on  this  work,  having  been  encouraged  by  many 
flattering  testimonials  of  approval  by  the  Press  and  the 
public  at  large.  He  has  introduced-  a great  many 
improvements  gathered  from  his  own  experiments, 
and  published  in  many  periodicals  of  the  country,  and 
vydiich  form  at  the  present  moment  a very  important 
branch  of  domestic  industry.  ’ The  soluble  glass  has,  of 
late,  become  paramount  in  the  arts,  as  many  trades  can- 
not dispense  with  it  in  their  pursuits,  and  more  so  since 
the  great  confiagration  of  the  City  of  Chicago,  v/hich 
took  place  on  the  9th  and  10th  of  October,  where  one- 
fifth  of  it  was  laid  waste  and  destroyed  ; all  the  public 
buildings,  churches,  court-house,  the  principal  business 
houses,  and  many  wooden-roofed  houses  inhabited  by 
poor  people.  This  disaster  has  aroused  in  the  minds  of 
mauy  men,  and  journalists  in  particular,  the  question 
whether  or  not  such  a catastrophe,  by  resorting  to  more 


4 Se 


IV 


INTEODUCTOEY. 


precautions  in  the  construction  of  buildings  could  not  be, 
in  future,  either  entirely  avoided,  or  conflagrations  of  any 
magnitude  be  stayed  in  the  sudden  progress  of  the  fiery 
element.  Well-informed  men  have  so  expressed  their 
belief  in  letters  to  the  Author,  that  the  steeples  of  high 
buildings  caught  from  the  sparks  flying  in  all  directions 
from  the  contagion,  and  could  with  ease  have  been  saved 
by  a judicious  management.  The  editor  of  the  Scientific 
American  of  November  11th  makes  the  following  perti- 
nent remarks  in  his  leader  resjoecting  the  great  fire,  which 
we  copy  here  with  alacrity,  for  they  coincide  entirely 
with  the^Author’s  ideas,  and  they  inspire  the  hope  that  all 
the  newspapers  in  the  United  States  may  take  due  notice 
of  such  valuable  hints  thrown  out,  and  copy  them  in  their 
local  papers,  so  that  all  their  readers  may  profit  thereby, 
and  follow  out  such  precautions  which  this  journal  recom- 
mends, and  whereby,  at  trifling  expense  and  trouble, 
millions  of  dollars  worth  of  property  can  be  saved  to 
owners  and  insurance  companies. 

He  speaks  of  suitable  building  material  in  the  follow- 
ing article : 

“ Recent  events  have  turned  the  attention  of  thoughtful 
people  to  a consideration  of  the  question  of  building  ma- 
terial for  large  towns.  It  no  longer  appears  proper  to 
permit  indiscriminate  constructions,  where  the  safety  of 
a Avhole  community  may  be  endangered.  We  have,  in 
large  cities,  superintendents  of  buildings,  but  they  gene- 
rally confine  their  attention  to  the  question  of  security 
against  falling,  and  not  to  the  character  of  the  building 
material,  excepting  in  so  far  as  wooden  structures  may 
be  prohibited  in  certain  districts.  There  would  now  ap- 
pear to  be  cogent  reasons  why  commissioners  should  be 
appointed  to  secure  greater  precautions  than  the  mere 
question  of  wood  and  iron.  A mixed  commission,  com- 
posed of  builders,  architects,  underwriters,  firemen  and 


INTRODUCTORY. 


V 


scientific  experts,  could  be  appointed  to  study  tbe  whole 
subject  and  report  thereon  to  the  government.  The  com- 
mission could  very  properly  decide  upon  the  survey  of 
streets,  and  the  width,  the  kind  of  pavement  and  flagging 
to  be  used.  They  could  lay  down  water  pipes  and  es- 
tablish hydrants  at  suitable  distances,  and  see  to  proper 
arrangements  for  extinguishing  any  fire's  that  might  arise ; 
but  the  most  important  duty  to  be  assigned  to  them 
would  be  the  control  of  building  material  in  certain 
sections  of  the  city. 

“ By  insisting  upon  the  construction  of  a row  of  build- 
ings, up  and  down  and  across  town,  as  nearly  fireproof 
as  it  is  possible  to  make  them,  a wall,  impervious  to  fire 
and  constituting  a barrier  impassable  to  'any  ordinary 
conflagration,  would  arrest  the  flames  and  save  whole 
sections  of  the  city.  A street,  built  up  entirely  of  fire- 
proof buildings,  would  be  a novelty  ; but  in  the  light  of 
recent  events,  it  would  appear  to  offer  great  protection, 
and  it  may  be  worth  while  to  designate  what  streets 
shall  be  of  this  character,  and  then  insist  upon  a com- 
pliance with  the  prescribed  style  of  building.  Having 
adopted  some  such  plan  as  this,  the  commission  would 
have  to  study  the  kind  of  building  material  best  adapted 
to  city  structures,  combining  security  and  durability  with 
reasonable  economy.  This  opens  up  the  whole  question 
of  the  comparative  value,  for  building  purposes,  of  wood, 
iron  and  stone.  They  tried  wood  in  Chicago,  without 
having  treated  any  of  the  material  with  the  numerous 
agents  that  have  been  recommended  to  render  it  incom- 
bustible ; and  the  sad  consequences  of  this  neglect  ought 
to  serve  as  a warning  to  all  other  cities.  If  the  wood 
had  been  saturated  with  soluble  glass,  it  could  not  have 
been  set  on  fire.  Silicate  of  soda,  or  soluble  glass,  can 
be  obtained  in  suffciently  large  quantities,  and  at  such 
reasonable  rates,  as  to  admit  of  the  preparation  of  the 


VI 


INTEODUCTORY. 


shingles,  clapboards,  and  all  exposed  portions  of  frame 
buildings.  Any  such  precaution  as  this  has  the  doubl® 
advantage  of  protecting  against  hre,  and  securing  against 
decay;  and,  in  the  long  run,  would  be  found  to  be  the 
greatest  economy. 

“ If  people  will  insist  upon  constructing  frame  build- 
ings in  large  towns,  they  ought  to  be  compelled  to  render 
them  essentially  fireproof  by  the  above  chemical  mixture. 
So  many  experiments  have  been  tried  with  soluble  glass, 
that  the  security  it  affords  against  fire  and  decay  may  be 
considered  as  fully  determined.  Wood  thus  prepared 
will  char  and  smolder,  but  will  not  burst  into  flame ; and 
hence  there  could  be  no  scattering  of  cinders  or  blowing 
about  of  firebrands. 

‘‘  Where  frame  buildings  are  tolerated,  the  fire  marshal 
might  justly  insist  upon  a chemical  preparation  of  the 
wood — an  operation  that  could  easily  enough  be  done,  if 
it  were  imperatively  required.  The  scientiflc  experts  on 
the  commission  would  be  apt  to  report  in  accordance 
with  the  princi23les  laid  down  above,  and  by  degrees  the 
dealers  in  lumber  would  learn  how  to  furnish  a building 
material  nearly  as  durable  as  iron. 

“ In  reference  to  the  use  of  iron  for  houses,  the  facts, 
that  it  is  employed  to  a large  extent,  and  that  we  are 
constantly  acquiring  greater  skill  in  its  manipulation  and 
management,  are  sufficient  2>roof  of  its  j)racticability.  In 
Chicago,  however,  this  material  proved  unavailing,  for 
the  reason  that  the  wooden  structures  made  a fire  hotter 
far  than  a blast  furnace  constructed  to  melt  2>ig  iron. 
No  iron  could  stand  such  a heat,  and  it  melted  down  like 
wax.  This  was  not  the  fault  of  the  iron,  but  caused  by 
the  neglect  to  prepare  the  wood  against  such  an  emer- 
gency ; and  no  one  will  be  likely  to  condemn  iron  struc- 
tures on  account  of  their  failure  in  Chicago. 

“ A third  building  material  is  stone,  and  this  may  be 


INTRODUCTOEY. 


VI 1 


divided  into  the  native  and  artificial.  There  are  a good 
many  varieties  of  stone  suitable  for  building  purposes  ; 
but  the  cost  of  quarrying,  transportation  and  working, 
is  so  great  in  this  country  as  almost  to  shut  this  mateiial 
out  of  competition.  This  objection  does  not  apply  to 
artificial  stone.  The  lime  and  sand  required  to  make 
artificial  stone  can  be  found  nearly  everywhere.  They 
can  be  mixed  by  simple  machinery,  and  require  no  labor 
to  cut  them  into  shape ; but  the  plastic  material  can  be 
run  into  any  kind  of  a mold,  where  it  dries  in  a few  hours, 
and  one  layer  after  another  can  be  carried  up-  in  marvel- 
ously short  time. 

“ For  rapidity  of  construction,  for  durability,  for  secu- 
rity against  fire,  for  warmth  and  ventilation,  for  dryness 
and  health,  for  economy,  for  architectural  effects,  there 
is  nothing  like  artificial  stone  ; and  we  look  upon  this 
material  as  the  most  suitable  for  cities,  and  as  probably 
destined  to  vsupersede  all  other.  It  only  needs  the  poiDular 
dissemination  of  information  on  the  subject  to  occasion  a 
demand  for  artificial  stone;  and  as  soon  as  such  a demand 
is  created,  this  material  can  be  furnished  in  any  quantity 
in  all  parts  of  the  country  ; and  we  shall  have  it  for  our 
cellars  and  our  ice  houses,  our  sewers,  cisterns,  w'ells, 
water  pipes,  paths,  roads,  schools,  churches,  dwelling 
houses  and  stores,  in  a way  that  will  make  us  wonder 
how  we  ever  performed  the  slow  and  tedious  labor  of 
hewing  out  stones  or  laying  up  brick,  when  we  could 
have  formed  a whole  house  at  one  casting — as  Kru23p 
pours  the  melted  steel  into  molds,  and  produces  a cannon 
of  any  size.” 

As  regards  the  Treatise  on  Glass  Maldng^  which  forms 
the  second  part  of  this  work,  it  may  be  worth  mentioning, 
that  many  of  the  western  glass  manufacturers  have  ex- 
pressed tlieir  wish  to  be  informed  of  the  late  improve- 
ments which  have  been  going  on  in  Europe,  as  far  as  they 


Vlll 


INTKODUCTORY. 


have  been  displayed  in  the  French  Exposition  of  1867, 
of  colored,  optical,  pl^te  and  other  glass,  all  of  which 
have  silex  as  the  base ; wherefore,  he  resolved  to  begin 
with  a fall  practical  description  of  the  glass  house,  from 
the  first  construction  to  the  manufacture  of  all  kinds  ol 
glass,  such  as  the  tumbler  and  mirror  glass.  The  Author 
believes  he  has  given  as  clear  and  succinct  information 
as  can  be  had,  in  a practical  manner. 

The  S)Oap  Maher’s  Gtdde,  which  forms  the  third  part 
of  this  work,  has  been  added  for  several  reasons ; the 
principal  of  which  was,  that  soluble  glass  and  fine  fiint 
have,  of  late  years,  been  largely  consumed  in  the  manu- 
facture of  soap  ; the  first  as  a useful  vehicle  for  domestic 
use,  and  for  washing  and  fulling  wool,  and  the  latter  for 
sophisticating  soaps  ; and  the  Author  has  taken  pains  to 
give  a full  description  of  the  manipulation  of  raw  ma- 
terials used  in  every  species  of  soap,  and  all  the  required 
information,  as  to  be  able  to  compete  with  any  manufac- 
turer; in  other  words,  this  treatise  is  intended  as  a full 
guide  in  soap  making. 

Since  the  Author  has  laid  out  this  work  to  be  alto- 
gether practical,  he  has  omitted  here  the  essays  on 
the  functions  of  carbonic  acid  and  limestones ; but  the 
alkalies  and  silex  in  the  former  edition  have  been  incor- 
porated in  the  present  work.  Trusting  that  the  public 
may  accept  with  indulgence  the  following  work,  if  in 
some  places  the  phraseology  or  othography  should  sound 
harsh  on  an  American  ear,  for  the  reason  that  the  impaired 
state  of  his  health  frequently  prevented  him  from  bestow- 
ing the  proper  attention  in  correcting  proofs ; he  now  de- 
livers it,  confidently  believing  that  it  may  prove  service- 
able and  useful  for  all  the  intended  objects. 


PREFACE  TO  THE  PRESENT  WORK. 


In  offering  the  present  edition  to  the  public,  the  Author 
begs  to  state,  that  he  felt  induced  to  change  his  jDro- 
gramme  from  the  first  edition,  for  the  following  reasons, 
viz. : The  long  and  detailed  discussions  on  soluble  glass 
in  the  first  having  been  received  with  great  favor,  it  was 
advisable  to  add  in  the  present  all  improvements  which 
have  been  suggested  by  various  authors  for  the  last  year ; 
he  has  devoted  in  the  present  work  two  hundred  pages 
in  the  description  of  the  materials  used  in  the  manufac- 
ture and  various  applications  of  the  same,  to  a great 
many  branches  of  domestic  industry. 

He  has  omitted  the  philosophical  essays  of  the  first 
edition,  on  account  of  his  resolution  to  publish  a practical 
book. 

The  whole  wmrk  is  divided  in  three  parts : 

I.  The  soluble  glass,  and  its  various  applications. 

IL  Glass  making  in  all  its  details. 

III.  Soap  making ; a guide  for  the  production  of  every 
species  of  soap,  the  family,  toilet  and  silicated. 

The  following  works  have  served  the  writer  in  his 
compilations  with  the  greatest  satisfaction,  such  as  Mus- 
]>rat’s  Encyclopedia,  where  the  subject  on  glass  is  so 
ably  treated.  And  in  his  guide  for  soap  making  he  has 
been  principally  assisted  by  I)r.  Adolph  Ott’s  book  on  the 
art  of  manufacturing  soap  and  candles. 


PREFACE  TO  FIRST  EDITION. 


The  object  of  this  Treatise  on  Soluble  or  Water  Glass, 
is  to  give  some  information  to  the  many  inquiries  which 
have  been  directed  to  the  Author  for  some  years  past,  in 
what  manner  and  purpose  this  valuable  preparation,  so 
highly  recommended  by  the  various  scientific  journals, 
can  be  usefully  employed.  There  is,  as  yet,  no  book 
published,  treating  on  all  its  applications,  with  the  excep- 
tion of  a pamphlet  in  French  by  Kuhlmann  in  1859,  con- 
taining mostly  memoirs  to  the  French  Academy,  and  the 
application  of  the  water  glass  by  calico  printers  and  cot- 
ton manufacturers.  It  is  for  this  reason  that  the  Author 
felt  the  necessity  of  compiling  all  that  is  scattered,  about 
the  various  uses  of  the  soluble  glass,  in  all  the  journals 
and  Patent  Olfice  reports.  Not  a day  passes  without  re- 
ceiving orders  for  samples,  either  in  dry,  liquid  or  jelly 
state,  with  particular  requests  for  exj)licit  directions  ; nor 
does  a day  pass  without  being  importuned  by  strangers 
and  curious  people,  all  desirous  for  information  how  the 
soluble  glass  would  answer  for  many  purposes  in  domestic 
economy.  The  soap  maker,  who  has  been  using  it  in 
Europe  and  this  country  for  a number  of  years,  wants  to 
know  more  on  the  subject  of  producing  a cheap  and  good 
soap.  For  slates,  for  a good  and  cheap  whitewash,  for 
a fireproof  paint,  for  a hoop  skirt  or  shirt  collar,  for  a 
mucilage,  a fire  and  waterproof  cement,  and  for  many 
hundred  other  uses,  the  inquiries  are  made;  and  thousands 
of  samples  have,  for  the  last  ten  years,  been  distributed 
to  the  inquisitive  and  speculative  applicants. 


PKEFAOE  TO  FIRST  EDITION. 


XI 


It  is  generally  known  that  the  Author  was  the  first  to 
introduce  the  soluble  glass  in  the  United  States,  and  has 
devoted  much  time  in  experimenting  with  it ; and  he  has 
succeeded,  after  many  fruitless  trials,  to  create  a demand 
in  many  branches  of  industry.  From  the  extensive  list 
of  patents  issued  in  Europe  and  the  United  States,  he  has 
collected  all  information,  along  with  that  obtained  from 
the  scientific  and  practical  journals,  and  experimenters 
will  find  in  this  Treatise  the  various  uses  and  applica- 
tions.. Kuhlmann’s  Pamphlet,  the  Mining  and  Engineer- 
ing Journal,  the  Transactions  of  the  American  Institute, 
the  Manufacturer  and  Builder,  Scientific  American,  the 
Annual  of  Scientific  Discovery,  have  all  furnished  ma- 
terial for  this  Treatise.  ’ 

Many  interesting  topics,  such  as  the  origin  of  saltpetre, 
the  nitrate  of  soda,  and  the  manufacture  of  blanc  fix, 
had  to  be  related,  and  will,  no  doubt,  interest  the  general 
reader. 

Particular  attention  has  been  bestowed  upon  the  for- 
mation of  hydraulic  cements  and  artificial  stone,  for  the 
reason  that  more  inquiries  and  experiments  are  performed 
in  this  branch  than  in  any  other  of  domestic  economy. 
The  natural  stones,  such  as  the  brown  stone,  sandstone, 
limestone  and  brick  building,  will,  sooner  or  later,  after 
an  exposure  to  the  atmospheric  elements,  and  rain  and 
frost,  become  decomposed ; cracks  and  fissures  will  then 
produce  the  deterioration,  while  coated  with  the  soluble 
glass  and  mixing  the  mortar  with  the  same  and  impreg- 
nating the  bricks,  much  is  gained  for  their  preservation. 

It  is  somewhat  remarkable,  that  long  before  this  the 
art  of  making  artificial  stone  has  not  been  brought  to 
perfection.  Yet,  if  we  may  judge  from  the  great  and 
increasing  variety  of,  processes,  patented  and  otherwise, 
which  now  press  their  claims  upon  public  notice,  the  time 
is  ripe  for  the  introduction  of  any  process  which  can 


XU 


PREFACE  TO  FIRST  EDITION. 


demonstrate  practically  its  capacity  to  fulfill  tlie  require- 
ments of  the  case.  Every  opportunity  has  been  afforded 
us  to  examine  and  test  specimens  of  artificial  stone,  and 
we  have  met  with  many  kinds  which  have  very  little 
merit.  Some,  however,  are  really  good  stones,  and,  as 
such,  must,  in  our  opinion,  come  largely  into  use. 

The  silicification  of  rail-road  sleepers,  wooden  rails  and 
blocks  for  pavement  is  in  importance  next  to  the  prepara- 
tion of  artificial  stone.  The  comparison  of  the  wooden 
and  iron  rails  has  also  been  clearly  stated  here,  and  the 
future  will,  no  doubt,  bring  to  light  many  facts  here 
stated,  but  not  yet  put  to  practice.  The  advantages  of 
the  wooden  block  pavement  over  all  other  kinds,  such  as 
Macadamizing,  graveling,  cinders,  boulders,  and  stone 
blocks,  are  numerous,  and  if  properly  laid,  will  withstand 
long  years  of  the  hardest  kind  of  travel;  and  there  are 
but  two  important  points  in  the  wooden  pavement  to  be 
observed,  which  are  a firm  and  even  foundation,  and  the 
good  silicification  of  the  foundation  planks  and  blocks. 

The  reason  why  the  Author  has  devoted  so  much  space 
upon  hydraulic  limes,  mortars,  paints,  whitewashes,  and 
the  preparation  for  guarding  timber  against  dry  rot  and 
conflagration,  is  solely  to  prove  and  make  it  plausible 
that  the  application  of  soluble  glass  possesses  great  ad- 
vantages, and  may,  with  very  little  expense,  give  addi- 
tional safeguards. 

The  formulae  and  directions  for  preparing  an  immense 
number  of  the  most  useful  vehicles,  cements  for  building 
and  side-walks,  paints,  varnishes,  &c.,  cannot  but  be 
very  acceptable. 


SOLUBLE  GLASS, 


Also  called  water  glass,  liquid  quartz,  or  alkaline 
silicate,  consists  essentially  of  silex  and  one  or  two 
alkalies  heated  to  fusion ; it  is,  therefore,  a silicate, 
either  as  silicate  of  potassa,  silicate  of  soda,  or  a mix- 
ture of  these  two  alkalies,  a silicate  of  potassa  and 
lime,  the  composition  of  Bohemian  glass,  or  a silicate 
of  soda  and  lime,  like  the  English  crown  or  spread 
glass  ; and  if  there  is  oxide  of  lead  added  to  the  mix- 
ture of  silex  and  alkalies,  and  heated  to  continued 
fusion,  we  obtain  thereby  a Hint  glass,  crystal  glass,  or 
strass,  a paste  used  in  mock  jewelry. 

According  to  the  quantity  of  alkali  employed  in 
the  mixture,  the  product  is  made  soluble  or  insoluble. 
Bottle  and  window  glass,  for  instance,  which  contain 
less  alkali  and  some  oxide  of  iron  and  alumina,  (clay,) 
are  more  difficult  of  fusion  than  other  kinds.  The 
soluble  glass  was  brought  to  practicable  uses  by  Pro- 
fessor Fuchs,  of  Munich,  in  Bavaria,  in  the  year  1823, 
by  igniting  strongly  in  a reverberatory  furnace  or 
crucible  for  six  hours,  a mixture  of  10  parts  of  pearl 
ashes,  15  parts  of  powdered  quartz,  or  fine  sand,  and 
1 part  charcoal ; the  mass  was  then  pulverized  and 
added  in  small  portions  to  boiling  water,  until  the 
whole  is  dissolved  and  evaporated  to  a specific  gravity 
of  1.25,  at  which  point  the  carbonic  acid  of  tlie  at- 

2 


14 


SOLUBLE  GLASS. 


mospheric  air  ceases  to  decompose  it.  The  highest 
concentration  of  the  liquid  is  42°  B.  5 when  still  more 
evaporated  it  is  obtained  in  a solid  form,  resembling 
common  glass,  but  much  softer  and  more  fusible. 
The  liquid  standing  about  30°  B.  is,  however,  the 
most  proper  menstruum  for  application  to  wood,  and 
preventing  the  same  from  being  attacked  or  kindled 
by  sparks  of  fire,  such  as  shingle  roofs,  wooden  bridges 
and  farm  houses.  Fuchs  prepared  four  different  li- 
quids, and  employed  them  in  his  experiments  : 

1.  The  simple  water  glass,  made  from  potassa. 

2.  The  soda  water  glass. 

3.  The  compound  of  both. 

4.  Another  liquid  which  he  used  for  fixing  paints 
on  a coating  on  wood,  and  called  the  jelly  liquid. 

In  order  to  demonstrate  the  utility  of  the  water 
glass  in  making  wood  fire-proof,  and  on  the  occasion 
of  the  burning  of  the  Boyal  Theatre  at  Munich,  a 
wooden  shanty  was,  by  order  of  the  King,  erected, 
and  coated  inside  and  outside  with  a weak  liquid  of 
silicate  of  potassa,  and  was  set  on  fire  on  each  corner  ; 
to  the  satisfaction  of  all  spectators  it  resisted  the  ele- 
ment nobly,  and  merely  charred  the  wooden  struc- 
ture without  producing  a life  fire  ; and  from  that  time 
the  water ^lass  was  introduced  in  Germany.  A few 
years  later  the  same  liquid  was  introduced  in  the 
manufacturing  districts  of  England  as  a substitute  for 
cow’s  dung  by  the  cotton  mills,  and  was  called  ‘‘  Dung- 
ing Salt.” 

The  author  having  studied  with  Doebereiner,  a 
professor  of  practical  chemistry  in  Jena,  was  engaged 


goLtJBLi:  GLASS. 


15 


In  experiments  on  water  glass,  and  who  proposed  an 
alteration  in  its  composition,  such  as  the  compound  of 
potash  and  soda,  or  72  parts  of  carbonate  of  potash, 
854  parts  of  carbonate  of  soda,  and  152  parts  of  linelj 
pulverized  quartz,  which  proved  to  be  a better  sub- 
stance, conceived  the  idea  that  water  glass  may  be 
prolitably  employed  in  this  country  for  many  purposes. 
In  company  with  ship  captains  and  builders  he  offered 
to  substitute  it  in  coppering  vessels,  which  is  attended 
with  that  expensive  metal,  the  copper  sheathing,  and 
undertook  to  prepare  the  ship’s  timbers  in  such  a 
manner  that  the  cells  of  the  wood  could  be  filled  up 
with  Silica,  or,  in  other  words,  to  silicify 'them,  and 
produce  a petrification  of  the  organic  substance,  all  of 
which  at  a very  inconsiderable  expense;  in  the  Brook- 
lyn  Navy  Yard,  he  was  permitted  by  the  Ordnance 
Department,  under  the  direction  of  Commodore 
Berry,  then  the  Captain  of  the  Yard,  to  perform  the 
experiments  with  the  spiles  on  the  various  docks, 
which  were  destroyed  by  the  worms  {Teredo  navalis) 
so  fast  that  they  had  to  be  replaced  every  three  years. 
Also  t1ie  cannon  balls  exposed  to  the  weather,  becom- 
ing rusty  and  worthless  in  a few  years,  were  varnished 
with  his  own  preparation,  and  the  addition  of  asphal- 
turn,  and  his  experiments  proved  highly  satisfactory, 
as  in  both  instances  of  applications  many  years  after- 
wards indicated  their  preservation. 

The  water  glass  was  neglected  for  many  years  ex« 
cept  by  the  military  authorities  in  Prussia,  and  we 
hear  that  the  soldiers  werfe  instructed  to  wash  their 
linen,  and  the  State  Prison  at  Spandau  introduced  it 
for  washing  the  prisoners’  under  garments  ; and  it  was 
proved  so  economical,  that  one  gallon  of  concentrated 


16 


SOLtJBLS  GLASS. 


liquid  was  sufficient  for  washing  1,000  pieces.  The 
soap  manufacturers  began  to  use  it  in  England  for 
producing  a cheap  soap.  Liebig  devoted,  in  the  year 
1850,  much  attention  to  the  subject,  and  at  the  same 
time  Kuhlmann  introduced  it  as  a new  paint  under 
the  name  of  stereochromic  painting,  for  ornamenting 
the  interior  of  houses.  He  applied  the  fluid  silicate  of 
potassa,  obtained  by  dissolving  flints  in  caustic  alkali, 
with  the  aid  of  water  of  a very  high  temperature,  to 
harden  chalk  and  porous  stone;  for  he  observed  that 
on  soaking  chalk  with  this  fluid  silicate,  a change 
took  place:  part  of  the  chalk,  combining  with  the 
silicic  acid  of  the  silicate  of  potash,  becoming  con* 
verted  into  silico  carbonate  of  lime,  the  carbonic  acid, 
thus  free,  combined  with  the  potash,  in  time,  particu* 
larly  when  assisted  by  heat-  and  dry  air,  the  coating 
of  silico  carbonate  was  found  to  pass  into  a true  com- 
pact deposit  of  silica,  hard  enough  to  scratch  glass. 
The  solution  of  silicate  of  potash  could  be  applied 
either  with  a brush  or  a syringe,  the  surface  being 
first  cleaned  and  scraped.  Three  applications  were 
considered  sufficient.  Although  successful  in  the  la- 
boratory, this  method  failed  when  applied  to  build- 
ings, because  a dry  atmosphere  is  needed  during  the 
whole  period  of  hardening.  Hot  long  after  this  sug- 
gestion had  been  made  by  Kuhlmann,  the  English 
manufacturer,  Kansorne,  of  Ipswich,  engaged  in  the 
manufacture  of  silicate  of  soda,  following  up  the  above 
experiments,  attempted  to  fix  the  solution,  when  ab- 
sorbed with  the  stone,  to  produce  a double  decompo- 
sition by  absorbing  another  solution,  thus  leaving  an 
insoluble  deposit  within  the  substance  of  the  absorb- 
ent stones  on  which  it  was  desired  to  act.  He  found 


SOLUBLE  GLASS. 


17 


that,  bj  a weak  acid  soliiHou,  he  could  set  free  tlie 
silica,  but  in  that  state  the  deposited  mineral  had  no 
coliesion.  Following  up,  however,  the  application  of 
the  fluid  silicate  by  a small  portion  of  chloride  of  cal- 
cium, (a  waste  product  from  the  salines  and  acetic  acid 
manufacturers,)  it  resulted  that  the  chlorine,  parting 
from  the  calcium,  attacked  the  soda  of  the  silicate, 
forming  common  salt,  which  is  easily  dissolved  away, 
while  the  silicic  acid,  set  free,  combining  with  the 
lime,  formed  with  it  silicate  of  lime.  This  mineral  is 
nearly  insoluble,  very  hard,  and  adheres  with  great 
tenacity  to  foreign  substances,  as  is  illustrated  in  com- 
mon mortar.  Silicate  of  lime  thus  formed  resists  car- 
bonic acid  and  dilute  sulphuric  acid,  and  is  little 
afiected  by  any  of  the  common  alkalies  or  ammonia. 

The  effect  of  this  treatment  on  stones  that  have  not 
already  been  inserted  into  buildings  has  Teen  very 
favorable  ; and  they  appear  to  have  stood  without  de- 
cay under  exposures  sufficient  to  have  produced  much 
injury  on  the  same  stone  unprotected  and  applied  on 
a large  scale  to  buildings  that  have  already  shown 
symptoms  of  decay,  the  result  is  less  satisfactory  ; but 
years  must  elapse  before  a very  decided  opinion  can 
be  given  on  the  process.  After  some  time  we  will  be 
able  to  see  the  result  in  the  Houses  of  Parliament  and 
Westminster  Abbey,  where  the  magnesian  limestone 
has  been  treated  by  this  process. 

A combination  of  Kuhlmann’s  process  wdth  a tem- 
porary wash  of  some  bituminous  substance  has  been 
tried  on  a large  scale  in  the  Speaker’s  Court  of  the 
Houses  of  Parliament,  by  Szereling,  which  will  like- 
wise be  decided  after  some  time  upon  its  superiority. 

The  manufacture  of  the  water  glass  or  soluble  sili- 


18 


SOLUBLE  GLASS. 


^cate,  or  soluble  glass,  has  only  been  known  since  our 
present  time,  although  the  various  kinds  of  glass,  imi- 
tation of  gems,  belongs  to  antiquity  ; for  Pliny  states 
that  glass  was  first  discovered  by  accident  in  Syria, 
at  the  mouth  of  the  River  Belus,  by  certain  merchants 
driven  thither  by  the  fortune  of  the  sea,  and  obliged 
to  continue  there  and  dress  their  victuals  by  making 
a fire  on  the  ground,  where  there  being  a great  store 
of  the  herb  'kali^  that  plant  burning  to  ashes,  its  salts, 
mixed  and  incorporated  with  sand  or  stones  fit  to 
vitrify  or  make  glass.”  The  word  kali  was  explained 
by  Boerhave  as  one  of  the  materials  of  glass,  salt  and 
sand  / the  salt  here  used  is  procured  from  a sort  of 
ashes,  brought  from  the  Levant,  called  polverine  or 
rochetta,  which  ashes  are  those  of  a sort  of  water  plant 
called  kali,  of  the  species  of  that  found  in  some  parts 
of  England,  called  frog-grass,  or  crab-grass,  cut  down 
in  summer,  dried  in  the  sun,  and  burnt  in  heaps,  either 
on  the  ground  or  on  iron  grates,  the  ashes  falling  into 
a pit,  grow  into  a hard  mass  or  stone,  fit  for  use.” 
This  material  evidently  means  the  kelp,  which  was 
burnt  and  converted  into  Barilla.  It  is  also  certain 
that  Kunkel,  in  1679,  states  that  the  art  of  glass  was 
already  brought  to  its  highest  perfection,  and  expressed 
that  Neri,  in  his  treatise  “ De  Arte  Yitraria,”  has 
communicated  complete  knowledge  of  artificial  gems. 
Much  is  said  of  flexible  glass  not  rotting,  of  a fusible 
or  soluble  glass,  of  wdiich  Yan  Helmont,  the  chemist 
of  the  first  part  of  the  seventeenth  century,  knew 
nothing.  The  improvements  in  the  manufacture  of 
the  soluble  glass,  particularly  that  of  soda,  were  of 
great  importance.  He  had,  in  the  first  place,  dis- 
carded the  sand,  which  he  did  not  find  compact 


SOLUBLE  GLASS. 


19 


enongh  for  producing  a good  paint,  and  substituted 
the  flints,  found  in  the  chalk  : this  species  of  silex  he 
exposes  under  a pressure  of  7-8  atmospheres,  in  an 
iron  cauldron,  to  a hot  soda  lye  standing  38°,  which 
process  was  patented  by  the  brothers  S*iemens,  in  the 
year  1845,  with  this  difierence,  that  they  produce  a 
liquid  at  a very  high  temperature  corresponding  in 
vapors  of  4-5  atmospheres,  by  which  process  they  ob- 
tain 3-4  times  the  quantity  of  silica  to  a thin  liquid. 

Liebig  proposes  the  employment  of  the  infusorial 
earth,  which  dissolves  readily  the  caustic  soda  lye, 
whereby  he  obtains  240  parts  of  silica  jelly  from  120 
parts  infusorial  earth,  and  75  parts  soda  ash.  It  is 
well  known  that  the  infusorial  earth  is  pretty  pure 
silica  of  87  per  cent,  and  8 per  cent,  water.  The  beds 
of  Bilin,  in  Bohemia,  and  belonging  to  the  fresh  water 
Tertiary,  have  a thickness  of  14  feet,  also  in  Planitz, 
in  Saxony.  Ehrenberg  estimates  that  about  18,000 
cubic  feet  of  the  siliceous  organisms  are  annually 
formed  in  the  harbor  of  Wismar,  in  the  Baltic  Sea  ; 
the  deposit  of  infusorial  earth  in  Richmond,  Ya.,  con- 
tains over  lUO  species,  and  forms  a thick  stratum. 


SIL'EX,  OR  SILICA. 


This  substance  is  an  oxide  of  siliciiim,  and  being 
the  main  body  of  our  preparation,  deserves  a full  and 
detailed  description. 

Silicium  is  the  metallic  basis  of  silica,  or  silex,  and 
is  equally  abundant  with  oxygen  as  a constituent  of 
tlie  solid  surface  of  the  globe,  also  constituting  a 
large  portion  of  aerolites,  from  the  region  of  space. 
This  metallic  base  was  discovered  by  Berzelius,  in  1823, 
and  is  obtained  artificially  in  the  following  manner : 
Well  dried  silico  fluoride  of  potassium,  10  parts,  are 
mixed  with  8 or  9 parts  potassium  in  an  iron  or  glass 
tube,  and  the  potassium  fused  and  stirred  with  the  salt 
by  an  iron  wire.  It  is  then  heated  by  a spirit  lamp, 
when  it  suddenly  becomes  ignited  from  the  reduction 
of  silica  by  the  potassium  forming  a brown  mixture  of 
fluoride  and  siliciuret  of  potassium.  It  is  thrown  in 
cold  water,  when  hydrogen  is  evolved,  the  potassium 
of  the  silica  not  being  oxydized  by  water  and  the  sili- 
cium separating.  When  the  effervescence  has  ceased, 
the  solution  is  poured  off,  fresh  cold  water  added  and 
poured  off,  until  it  ceases  to  be  alkaline,  when  boiling 
water  is  used  to  wash  the  silicium  as  long  as  it  extracts 
any  thing. 

Silicium  is  inflammable  in  the  air,  by  heat,  about 
one-third  burning  to  silica,  which,  removed  by  fluo- 
hydric  acid,  leaves  a dark,  chocolate,  brown  powder, 
heavier  than  oil  of  vitriol,  is  combustible  either  in  the 


21 


BILEX,  OR  SILICA. 

air  or  oxj^gen,  or  even  when  gently  ignited  with  salt- 
petre. 

Silica,  or  oxide  of  siliciiim,  is  synonymous  wnth 
silicic  acid,  silex  and  pure  sand,  or  quartz,  in  its  vari- 
ous forms  and  appearances,  and  constitutes  a very  large 
proportion  of  the  solid  crust  of  the  globe  ; is  the  prin- 
cipal constituent  of  all  simple  minerals,  and  forms  a 
greater  variety  of  salts  than  any  other  acid.  It  is 
easily  prepared  pure  from  powdered  quartz,  sand,  fel- 
spar, or  other  silicious  minerals,  by  fusing  them  with 
four  times  their  weight  of  a mixture  of  carbonate  of 
potassa  and  soda,  or  by  either  carbonate  alone,  dis- 
solving them  in  dilute  muriatic  acid,  filtering  and 
evaporating  the  solution  to  dryness  by  a gentle  lieat, 
digesting  in  muriatic  acid,  filtering  and  washing  with 
hot  water. 

This  silica  has  two  modifications,  the  one  soluble  in 
water  and  acids,  the  other  insoluble.  The  soluble  is 
that  obtained  in  the  above  process  for  preparing  silica, 
and  is  always  formed  by  fusing  silicates  with  alkalies, 
but  may  also  be  formed  by  boiling  fine  Silex  with 
strong  alkaline  solutions. 

It  is  soluble  in  water  and  acids,  and  when  the  solu- 
tions are  concentrated  it  usually  separates  as  a jelly, 
[gelatinous  silica,]  and  when  evaporated  to  dryness, 
passes  into  the  insoluble  modification. 

Silica  is  a white,  gritty  powder,  insoluble  in  water 
and  acids,  infusible  in  the  highest  heat  of  our  furnaces, 
but  fusible  in  a stream  of  oxygen  driven  through  an 
alcohol  flame.  It  fuses  in  this  case  to  a clear  glass, 
which  may  be  drawn  out  into  flexible  threads.  When 
the  fused  bead  is  drop]>ed  in  water,  it  becomes  so  hard 
as  to  indent  a steel  pestle  and  mortar.  It  is  the  fee- 

2* 


22 


SILEX,  OE  SILICA. 


blest  acid  at  common  temperatures,  but  by  a high  beat 
can  expel  all  volatile  acids. 

Quartz  is  found  in  nature  crystalized  in  a great 
variety  of  forms,  the  rhombohedral  prevailing,  and  for 
the  most  part  hemiliedral  to  the  rhombohedron,  or 
tetrahedral  to  the  hexagonal  prism.  The  annexed  two 
figures  give  some  idea  of  its  occurrence  : 


The  cleavage  is  very  indistinct,  sometimes  efiected 
by  plunging  a heated  crystal  in  cold  water.  The 
crystals  are  either  very  short  or  very  much  elongated, 
sometimes  fine  acicular  usually  implanted  by  one  ex- 
tremity of  the  prism,  occasionally  twisted  or  bent. 
The  prismatic  faces  commonly  striated  horizontally, 
and  thus  distinguishable,  in  distorted  crystals  from  the 
pyramid.  Crystals  often  grouped  by  juxtaposition, 
not  proper  twins,  frequently  in  radiated  masses  with 
a surface  of  pyramids,  or  in  druses  having  a surface  of 
pyramids  or  short  crystals.  Herkimer  and  Ulster 
counties,  of  the  State  of  Hew-York,  produce  quartz 
crystals  of  the  most  complicated  forms,  which  occur 
from  the  size  of  a pin’s  head  to  that  of  a foot.  Quartz 
is  also  found  massive,  from  the  coarse  or  fine  granular 
to  fiint-like  or  crypto-crystaline  ; sometimes  mammil- 
lary stalactitic,  and  in  concretionary  forms. 


i 


i 


SILEX,  OR  SILICA. 


23 


Quartz  has  a hardness,  7,  and  a specific  gravity  of 
2.65  ; a vitreous  lustre  sometimes  inclining  to  resinous  ; 
splendent  and  nearly  dull ; is  colorless  when  pure,  but 
often  having  various  shades  of  yellow,  red,  brown, 
green,  blue  and  black.  The  streak  is  white  of  pure 
varieties  ; of  impure  often  the  same  a§  the  colors,  but 
much  paler.  Quartz  is  transparent  and  opaque  ; its 
fracture  is  perfect  conchoidal  and  subchonchoidal,  is 
tough,  brittle  and  friable.  The  polarization  of  quartz 
is  circular,  there  being  a colored  centre  instead  of  a 
central  cross,  and  the  rings  of  color  around  enlarging 
as  the  analyzer  is  turned  to  the  right  in  right-handed 
crystals,  or  left,  in  left-handed,  and  colored  spirals  are 
seen,  which  rotate  to  the  right  or  left  when  the.incident 
light  and  emerged  light  are  polarized,  one  circularly, 
and  the  other  plane. 

Pure  silica,  which  has  the  symbol  of  Si,  consists  of 
53.33  parts  oxygen,  and  46.67  silicon=100.  It  is  un- 
altered if  brought  alone  before  the  blow-pipe,  but 
with  soda  it  dissolves  with  effervescence  ; it  is  unacted 
upon  by  any  salt  of  phosphorus ; it  is  only  soluble  in 
fluohydric  acid.  There  are  two  varieties  of  quartz  in 
existence  : 

I.  The  crystalized,  or  phenocrystaline,  w’hich  is 
vitreous  in  lustre. 

II.  The  fluid-like,  massive,  or  crypto-crystaline. 

The  first  division  includes  all  ordinary  vitreous 
quartz,  whether  having  crystaline  faces  or  not ; while 
the  second  variety  has  been  acted  upon  somewhat 
more  by  'attrition  and  chemical  agents,  as  fluoric  acid, 
than  those  of  the  first. 


24 


SILEX,  OR  SILICA. 


I.  The  following  species  of  quartz  belong  to  the  phe- 
nocrjstaline,  or  vitreous  varieties  : 

1.  The  ordinary  crjstalized  quartz,  rock  crystal, 
which  is  the  colorless  quartz,  or  nearly  so,  whether  in 
distinct  crystals  or  not. 

a.  The  regular  crystals,  or  limpid  quartz. 

h.  The  right-handed  crystals. 

c.  Left-handed  crystals. 

d.  Cavernous  crystals,  having  deep  cavities  par- 

allel to  the  faces,  occasioned  by  the  interfer- 
ence of  impurities  during  their  formation. 

e.  Cap  quartz,  made  up  of  separable  layers  or 

caps,  owing  to  the  deposit  of  a little  clayey 
material  at  intervals  in  the  progress  of  the 
crystal. 

f.  Drusy  quartz,  a crust  of  small  or  minute 

quartz  crystals. 

g.  Radiated  quartz,  often  separable  into  radiated 

parts,  having  pyramidal  terminations. 

h.  Fibrous,  rarely  delicately  so,  from  Cape  of 

Good  Hope. 

2.  Asteriated  quartz,  star  quartz,  containing  within 
the  crystal  whitish  or  colored  radiations  along  the  di- 
ametral planes.  Part,  if  not  all,  asteriated  quartz  is 
asteriated  in  polarization,  as  already  remarked. 

3.  Amethystine  quartz,  amethyst,  clear,  purple  or 
blueish- violet ; the  colbr  is  supposed  to  be  due  to 
manganese;  the  shade  of  violet  is  usually  deepest  pa- 
rallel to  the  planes  R. 

4.  Rose,  rose  red  or  pink  quartz.  It  becomes  paler 
on  exposure,  commpn,  massive;  and  then  usually 


25 


SILEX,  OR  SILICA. 

much  cracked,  lustre  sometimes  a little  greasy.  The 
action  is,  according  to  Fuchs,  due  to  titanic  acid  ; the 
general  impression  is,  however,  that  its  color  is  owing 
to  manganese. 

5.  Yellow,  false  topaz,  yellow  and  pellucid,  or 
nearly  so,  resembling  somewhat  yellow  topaz  ; but 
very  different  in  crystalization,  and  in  absence  of 
cleavage. 

6.  Smoky  quartz ; the  Cairngorm  stone.  It  is 
smoky  yellow  to  smoky  brown,  and  often  transparent, 
but  varying  to  brownish  black,  and  then  nearly 
opaque,  in  thick  crystals.  The  color  is  probably  due 
to  titanic  acids,  as  crystals  containing  rutile  are  usu- 
ally smoky.  It  is  called  Cairngorm,  from  the  locality 
in  Scotland. 

7.  Milky,  milk  white,  and  nearly  opaque;  lustre 
often  greasy,  called  then  greasy  quartz. 

8.  Siderite,  or  sapphire  quartz,  of  indigo,  or  Berlin 
blue  colors.  A variety  of  quartz  occurring  in  an  im- 
pure limestone  at  Colling,  in  Salzburg. 

9.  Sagenitic,  containing  within  acicular  crystals  of 
other  minerals  : these  acicular  crystals  may  be  rutile, 
or  black  Tourmaline,  or  Goethite,  stilbite,  asbestos, 
actinolite,  hornblende,  or  epidote. 

10.  CaCs  eye,  exhibiting  opalescence,  but  without 
prismatic  colors,  especially  when  cut  in  cabochon,  an 
effect  due  to  fibres  of  asbestos. 

11.  Aventurine  quartz,  spangled  with  scales  of  mica 
or  other  mineral. 

12.  Impure  quartz,  from  the  presence  of  distinct 
minerals  distributed  densely  through  the  mass,  such 
as  ferruginous,  either  red  or  yellow  oxide  of  iron, 


26 


SILEXj  OR  SILICA. 


chloritic  from  ^chlorite,  actinolitic,  micaceous,  arena- 
ceous owing  to  sand. 

Quartz  crystals  also  occur  penetrated  by  various 
minerals,  as  topaz,  corundum,  cbrysoberyl,  garnet, 
different  species  of  hornblende  and  Pyroxene  groups, 
kyanite,  zeolites,  calcite  and  of  rutile,  stilbite,  hema- 
tite, Goetliite,  magnetite,  fluorite,  gold,  silver,  anthra- 
cite, &v,.  As  quartz  has  been  crystalized  through  the 
aid  of  hot  waters  or  of  steam  in  all  ages  down  to  the 
present,  and  is  the  most  common  ingredient  of’  rocks, 
there  is  good  reason  Avhy  it  should  thus  be  found  the 
enveloper  of  other  crystals.  . 

13.  Quartz  containing  liquids  in  cavities.  These 
liquids  are  seen  to  move  with  the  change  of  position 
of  the  crystal,  provided  an  air  bubble  be  present  in 
the  cavity ; they  may  be  detected  also  by  the  refrac- 
tion of  light ; the  liquid  is  either  pure  water,  or  a 
mineral  solution,  or  petroleum-like  liquid, 

II.  The  crypto-crystaline  varieties  of  quartz  are  the 
following : 

1.  Chalcedony  ; it  has  the  lustre  nearly  of  wax,  and 
is  either  transparent  or  translucent ; the  color  is  white 
grayish,  pale  brown  to  dark  brown,  black,  tendon 
color  common,  sometimes  delicate  blue ; also  of  other 
shades,  and  then  having  other  names ; it  is  often 
mammillary,  botryoidal,  stalactitic,  and  occurring  lin- 
ing or  tilling  cavities  in  rocks. 

2.  Carnelian  ; a clear  red  chalcedony,  pale  to  deep 
in  shade,  also  brownish  red  to  brown  ; the  latter  called 
sardonyx,  reddish  brown  by  transmitted  light. 

3.  Chrysoprase ; an  apple  green  chalcedony  ; the 
color  is  due  to  the  presence  of  oxide  of  nickel. 


27 


SILEX,  OR  SILICA. 

4.  Prase  ; translucent  and  dull  leek  green  ; taking 
its  name  from  the  Greek  a leek. 

6.  Plasma  ; a rather  bright  green  to  leek  green,  and 
sometimes  nearly  emerald  green  color,  and  sub-trans- 
lucent or  feebly  translucent,  sometimes  dotted  with 
white. 

Heliotrope,  or  bloodstone,  is  the  same  stone  essen- 
tially, with  small  spots  of  red  jasper,  looking  like 
drops  of  blood. 

The  jasper  of  the  ancients- was  a semi-transparent 
or  translucent  stone,  and  included,  in  Pliny’s  time, 
all  bright  colored  chalcedonj^  excepting  the  carne- 
lian  ; the  same  author  gives  special  prominence  to  sky 
blue  and  green,  and  mentions  also  a shade  of  purple, 
a rose  color,  the  color  of  the  morning  sky  in  autumn  ; 
sea  green,  serpentine  color,  (yellow,  like  serpentine,) 
smoke  color,  but  in  general  there  is  a tinge  of  blue, 
whatever  the  shade. 

6.  Agate;  a variegated  chalcedony;  the  colors 
are  either  banded  or  in  clouds,  or  due  to  visible  impu- 
rities. 

(Banded  agate.)  where  the  bands  form  delicate 
parallel  lines  of  white,  tendonlike,  waxlike,  pale  and 
dark  brown  and  black  colors,  and  sometimes  bluish 
and  other  shades,  they  follow  waving  or  zigzag 
courses,  and  are  occasionally  concentric  circular,  as  in 
the  eye  agate.  The  tine  translucent  agates  graduate 
into  coarse  and  opaque  kinds.  The  bands  are  the 
edges  of  layers  of  deposition,  the  agate  having  been 
formed  by  a deposit  of  silica,  from  solutions  intermit- 
tently supplied  in  irregular  cavities  in  rocks,  and  de- 
riving their  concentric  waving  courses  from  the  irreg- 
ularities  of  the  walls  of  the  cavity.  As  the  cavity  can- 


28 


8ILEX,  OB  8ILI0A. 


not  contain  enough  of  the  solution  to  fill  it  with  silica, 
an  open  hole  has  been  supposed  to  be  retained  on  one 
side  to  permit  the  continued  supply,  but  it  is  more 
probable  that  it  passes  through  the  outer  layers  by 
osmosis,  the  denser  solution  outside  thus  supplying 
silica  as  fast  as  it  is  deposited  within.  The  colors  are 
due  to  traces  of  organic  matter,  or  oxides  of  iron, 
manganese,  or  titanium,  and  to  differences  in  rate  of 
deposition.  The  layers  differ  in  porosity,  and  there- 
fore in  the  rate  at  which  they  are  etched  by  fluoric 
acid,  the  etching  process  brings  out  the  different  lay- 
ers, and  makes  engravings  that  will  print  exact  pic- 
tures of  the  agate.  Owing  also  to  the  unequal  po- 
rosity, agates  may  be  varied  in  color  by  artificial 
means. 

Irregularly  clouded  agate,  the  colors  various,  as  in 
banded  agate. 

A whitish,  clouded  variety,  which  Pliny  has  de- 
scribed and  given  fully  the  characters. 

Colored  agate,  due  to  visible  impurities ; a moss 
agate,  or  mocha  stone,  filled  with  brown  moss-like  or 
dentritic  forms,  distributed  through  the  mass  of  den- 
tritic  agate,  containing  brown  or  black  dentritic  mark- 
ings. These  two  have  been  fully  described  by  Pliny 
as  dentrachates. 

There  are  also  eight  agatized  woods,  wood  petrified 
with  clouded  agate. 

7.  Onyx,  like  agate,  in  consisting  of  layers  of  dif- 
ferent colors,  but  the  layers  are  in  even  planes,  and 
the  banding  therefore  straight,  and  hence  its  use  for 
cameos,  the  head  being  cut  in  color,  and  another  serv- 
ing as  the  background. 

T^he  colors  of  the  best  are  perfectly  well  defined, 


29 


STLEX,  OR  BILICA. 

and  white  and  black,  or  white,  brown  and  black  al- 
ternate. 

8.  Sardonyx,  like  onyx  in  structure,  but  includes 
layers  of  carnelian,  along  with  others  of  white,  or 
whitish  and  brown,  and  sometimes  black  colors. 

9.  Agate  jasper.  An  agate  consisting  of  jasper, 
with  veinings  and  cloudings  of  chalcedony. 

10.  Siliceous  sinter.  Irregular  cellular  quartz, 
formed  by  deposition  from  waters  containing  silica, 
or  soluble  silicates  in  solution. 

11.  Flint.  ' Somewhat  allied  to  chalcedony,  but 
more  opaque  and  of  all  colors,  usually  gray,  smoky 
brown  and  brownish  black.  The  exterior  is  often 
whitish,  from  mixture  with  lime  or  chalk,  in  which 
it  is  imbedded.  Lustre  barely  glistening,  sub  vitre- 
ous; breaks  with  a deeply  conchoidal  fracture  and  a 
sharp  cutting  edge.  The  flint  of  the  chalk  formation 
consists  largely  of  the  remains  of  infusoria,  sponges, 
and  other  marine  productions.  This  mineral  con- 
tains, according  to  Fuchs,  partly  soluble  silica. 

12.  Hornstone.  It  resembles  flint,  is  more  brittle, 
and  fracture  more  splintry.  Chert  is  a term  often 
applied  to  hornstone,  and  to  any  impure  flinty  rock, 
including  the  jaspers. 

13.  Easanite,  Ij^dian  stone,  or  touchstone.  A vel- 
vet black  siliceous  stone  or  flinty  jasper,  used  on  ac- 
count of  its  hardness  and  black  color  for  trying  the 
purity  of  the  precious  metals.  The  color  left  on  the 
stone  after  rubbing  the  metal  across  it  indicates  to 
the  experienced  eye  the  amount  of  alloy.  It  is  not 
splintry  like  the  hornstone  : it  passes  into  a compact, 
flssile,  siliceous  or  flinty  rock,  of  grayish  or  other  col- 


30 


SILEX,  OR  SILICA. 


ors,  called  siliceous  slate,  and  resembles  ordinary  jas- 
per, of  various  shades. 

14.  Jasper.  An  impure  opaque  colored  quartz.] 

a.  The  reducing  to  hematite,  or  sesquioxide  of 
iron. 

h.  The  yellow  or  brown,  colored  by  the  hj^drous 
sesquioxide  of  iron,  and  becoming  red  when 
so  heated  as  to  drive  off  the  water. 

c.  The  dark  green  and  brownish  green. 

d.  The  grayish  blue. 

e.  Blackish  or  brown  black. 

f.  Striped  or  ribbon  jasper,  having  the  colors  in 

broad  stripes. 

g.  Egyptian  jasper  in  nodules,  which  are  zoned 

in  brown  and  yellow  colors. 

Porcelain  jasper  is  nothing  but  a baked  clay,  and 
differs  from  true  jasper  in  being  fusible  on  the  edges 
before  the  blowpipe.  Bed  porphyry,  or  its  base,  re- 
sembles jasper,  but  is  also  fusible  on  the  edges,  being 
usually  an  impure  felspar. 

Quartz  is  also  found  in  the  following  forms  : 

1.  Granular  quartz,  or  quartz  rock,  which  consists 
of  quartz  grains  very  firmly  compacted,  the  grains 
often  hardly  distinct. 

2.  Quartzose  sandstone. 

3.  Quartz-conglomerate.  A rock  made  of  pebbles 
of  quartz  with  sand.  The  pebbles  are  sometimes 
jasper  or  chalcedony,  and  make  a beautiful  stone 
when  polished. 

4.  Itacolumite,  or  flexible  sandstone.  A friable 
sand  rock,  consisting  mainly  of  quartz  sand,  but  con- 


SILEX,  OR  SILICA. 


31 


taining  a little  talc,  and  possessing  a degree  of  flexi- 
bility when  in  thin  laminae. 

5.  Euhrstone.  A cellular  flinty  rock,  having  the 
nature  in  part  of  coarse  chalcedony. 

6.  Pseudomorphous  quartz.  Quartz  appears  also 
under  the  forms  of  many  of  the  mineral  species, 
which  it  has  taken  through  either  the  alteration  or 
replacement  of  crystals  of  those  species.  The  most 
common  quartz  pseudomorphs  are  those  of  cal  cite, 
baryta,  fluorite  and  siderite.  Tabular  quartz,  Hay- 
torite,  Beckite,  Babel  quartz,  silicified  shells  and 
silicifled  wood  are  found  pseudomorphized  by  other 
minerals,  either  of  carbonate  lime,  Datholite,  fluor- 
spar, shells  and  wood.  The  texture  of  the  wood,  for 
instance,  is  well  retained,  it  having  been  formed  by 
the  deposit  of  silica,  from  its  solution  in  the  cells  of 
the  wood,  and  Anally  taking  the  place  of  the  walls  of 
the  cells  as  the  wood  itself  disappeared. 

Dissolved  quartz,  or  liquid  silica,  occurs  often  in 
heated  natural  waters,  as  those  of  the  Geysers  of  Ice- 
land, New-Zealand  and  California,  mostly  as  a soluble 
alkaline  silicate. 

Quartz  is  one  of  the  essential  constituents  of  granite, 
sienite,  gneiss,  mica,  schist  and  many  related  rocks. 
As  the  principal  constituent  of  quartz  rock  and  many 
sandstones ; as  an  essential  ingredient  in  some  trachyte 
porphyry,  &c. ; as  the  veinstone  in  various  rocks,  and 
for  a large  part  of  mineral  veins  ; as  a foreign  mineral 
in  the  cavities  of  trap,  basalt  and  related  rocks,  some 
limestones,  &c.,  making  geodes  of  crystals  or  of  chal- 
cedony, agate,  carnelian,  &c.,  as  imbedded  nodules  or 
masses  in  various  limestones  containing  the  flint  of 
the  chalk  formation,  the  hornstone  of  other  limestones  ; 


SILEX,  OR  SILICA. 


82 

these  nodules  becoming  sometimes  layers  or  masses  of 
jasper  occasionally  in  limestone.  It  is  the  principal 
material  of  the  pebbles  of  gravel  beds  and  of  the  sands 
of  the  seashore  and  river  sandbeds. 

Independent  of  the  quartz  proper,  as  has  been  just 
described,  nature  produces  a vast  many  minerals 
composed  either  solely  of  silica,  with  slight  variations 
in  their  degree  of  hardness  or  specific  gravity,  such  as 
the  following: 

The  opal,  which  is  subdivided,  in 

1.  The  precious  opal^  exhibiting  a play  of  delicate 
colors. 

2.  The  fire  op>dl,  of  hyacinth  red  to"  honey-yellow 
colors. 

3.  The  girasol^  of  bluish  white  color,  with  reddish 
reflections  in  a bright  light. 

4.  The  common  opal^  in  part  translucent,  and  milk- 
white  to  greenish,  yellowish,  bluish.  Resin  opal,  wax 
or  honey  color,  with  resinous  lustre.  Olive  green 
opal  ; brick-red  opal  ; hydrophane,  a translucent 
opal,  whitish  or  light  colored,  adheres  to  the  tongue, 
and  becomes  more  translucent  or  transparent  in  water, 
wherefore  its  name.  An  orange,  yellow  opal,  called 
Forcherte  ; it  is  colored  by  orpiment. 

6.  Cachelong,  Opaque  and  bluish  white,  porcelain 
white ; often  adheres  to  the  tongue. 

6.  Opal  agate.  Agatelike  in  structure,  but  consist- 
ing of  opal  of  difierent  shades  of  color. 

T.  Menilite.  In  concretionary  forms,  tuberose, 
reniform  ; opaque,  dull  gray  and  grayish  brown. 

8,  Jaspopal.  An  opal,  containing  some  yellow 
oxide  of  iron,  and  having  the  color  of  yellow  jasper. 


BlLEX,  OR  SILICA.  33 

9.  Wood  opal.  Wood  petrified  bj  opal. 

10.  Hyalite.  Clear  as  glass  and  colorless,  consti- 
tuting globular  concretions  and  crusts. 

11.  Fioidte^  or  siliceous  sinter ; also  called  pearl 
sinter,  from  Santa  Fiora,  in  Italy,  and  other  volcanic 
rocks,  formed  from  the  decomposition  of  the  siliceous 
minerals  of  volcanic  rocks,  or  from  the  siliceous  waters 
of  hot  springs. 

12.  Float  stone  j also  called  swimming  quartz  ; is 
light,  concretionary  or  tuberose  masses,  white  or 
grayish,  sometimes  cavernous. 

13.  Tripolite.  Infusorial  earth  ; formed  from  the 
siliceous  shells  of  diatomous  and  other  microscopic 
species,  occurring  in  deposits  often  miles  in  area,  either 
uncompacted  or  moderately  hard. 

a.  Infusorial  earthy  or  earthly  tripolite,  is  a very 
fine  grained  earth,  looking  often  like  an 
earthy  chalk  or  clay ; but  harsh  to  the  feel, 
and  scratching  glass,  when  rubbed  on  it. 

h.  Bandanite  / a kaolin-like  variety  from  France. 

G.  Tripoli  slate.  A slaty  or  thin  laminated  va- 
riety ; fragile,  often  mixed  with  clay,  mag- 
nesia and  oxide  of  iron. 

d.  Alumocalcite.  A milk-white  material,  very 
light,  having  a hardness  of  only  1 to  IJ,  and 
a sp.  gr.  of  2.171,  and  probably  a variety  of 
tripolite. 

This  mineral  is,  probably,  the  most  economical  and 
useful  material  for  the  manufacture  of  the  soluble  glass. 

The  opal  family  is  likewise  a quartz,  but  a little 
softer  and  contains  some  water,  is  soluble  in  a heated 
solution  of  potash,  while  quartz  is  not. 


u 


on  SILICA. 


In  England  and  France  the  flints  from  the  chalk  are 
mostly  employed  in  the  manufacture  of  soluble  glass  ; 
but  in  the  United  States  clear  sand,  from  the  river- 
bed of  New-Jersey  and  Mississippi  rivers,  are  solely 
used  in  its  manufacture.  Sand  generally  consists  of 
particles  of  quartz,  but  there  is  also  a granitic  sand, 
containing  particles  of  felspar  as  well  as  quartz,  where 
it  has  not  been  long  enough  exposed  to  meteoric  agents 
to  decompose  the  felspar.  Sand  Usually  consists  of 
grains  more  or  less  rounded,  but  sometimes  angular, 
and  then  preferable  for  mortar.  There  are  several 
varieties  of  the  sandstone,  such  as  micaceous^  argilla- 
ceous^ marly  and  flexible.  Common  sand  is  mainly 
comminuted  quartz.  Gravel  is  a mixture  of  sand 
wflth  pebbles.  Volcanic  sand  is  sand  of  volcanic 
origin  ; either  the  cinders  or  ashes,  or  comminuted 
lava.  Alluvial  sand  is  the  earth  deposited  by  run- 
ning streams,  especially  during  times  of  flood  ; it  con- 
stitutes the  flats  on  either  side  of  the  stream,  and  is 
usually  in  thin  layers,  varying  in  fineness  or  coarse- 
ness, being  the  result  of  successive  depositions.  In 
order  to  use  the  sand  for  the  manufacture  of  soluble 
glass,  which  shall  equal  that  manufactured  from  flint, 
or  infusorial  or  siliceous  earth,  it  is  best  to  digest  the 
sand  with  chlorohydric  acid,  which  is  capable  of  dis- 
solving all  the  foreign  substances,  and  then  by  frequent 
washings  and  dryings  in  the  sun,  produces  a pretty 
pure  silica.  Iron,  clay,  lime,  which  are,  more  or  less, 
found  in  the  mud,  may  easily  be  detected  by  the  vari- 
ous chemical  tests,  such  as  by  ammonia,  the  iron  ; by 
oxalate  of  ammonia,  the  lime  ; and  clay,  by  carbonate 
of  soda. 

If  the  pure  crystalized  quartz,  flint  or  hornstone 


sileX,  on  siLidA. 


glioiild  be  used  for  the  manufacture,  the  same  must  be 
reduced  into  coarse  or  granular  condition,  which  is 
effected  by  calcining  the  mineral,  and  when  red  hot, 
cold  water  is  thrown  over  it,  whereby  it  becomes  dis-  ^ 
integrated  and  falls  to  pieces,  and  it  is  then  ground  in 
mills  used  by  the  glass  manufacturers. 

Before  closing  the  chapter  of  silica,  it  must  be  stated 
that  nature  has  given  us  a vast  variety  of  silicates  ; 
that  the  alkaline  silicates  of  soda,  potash  and  lime, 
which  are  called  the  soluble  silicates,  are  spread  over 
the  globe  in  such  quantities,  like  oxygen  compounds, 
with  the  addition  of  many  other  bases  in  nature,  that 
there  are  very  few  mineral  substances  known  in  which 
silica,  representing  the  acid,  is  not  combined  with  the 
various  elements,  and  forming  silicates  which  are  again 
divided  in  anhydrous  and  hydrous  silicates,  all  of  them 
having  ternary  oxygen  compounds.  The  anhydrous 
silicates  are  again  subdivided,  as  1.  Bisilicates  / 2. 
Unisilicates  and  3.  Suh- silica, tes  ; while  the  hydrous 
silicates  are  again  divided  in  various  sections.  The 
whole  crust  of  the  globe  consists  in  silicates.  The 
felspar  mica  is  a pure  silicate.  We  have  a soda  fel- 
spar, and  a potash  felspar,  and  a lime  felspar,  while 
the  mica  is  a compound  of  silica  combined  with  some 
other  bases,  such  as  alumina,  magnesia,  &c.  The 
zeolites  form  a large  class  of  silicates,  which  resemble 
the  felspar,  but  contain  water,  and  are  less  hard  and 
more  fusible,  such  as  the  analcime,  chabasite,  stilbite, 
heulandite,  &c. 

THE  ALKALIES,  &c. 

In  the  manufacture  of  soluble  glass,  the  alkalies 
are,  in  importance,  next  to  the  quartz  or  silica,  such 


36 


SILEX,  OR  SILICA. 

as  the  soda  and  potash,  both  of  which  are  employed  as 
the  carbonates,  which  ought  to  be  pure. 

The  carbonate  of  potash,  which  is  the  pearlash, 
must  be  free  from  foreign  saline  substances.  The 
glass  manufacturers  prepare  that  material  by  washing 
it  freely  with  water  and  evaporating  the  solution  to 
the  formation  of  a precipitate  of  salt,  and  then  the 
water  is  run  off. 

The  Soda  emploj^ed  in  the  manufacture  is  the  soda 
ash  of  comitierce,  and  is  never  pure  enough,  contain- 
ing water  and  other  salts,  which  ought  to  be  removed 
from  it  by  dissolving,  crystalizing,  and  then  calcina- 
tion of  the  crystals. 

Suljphate  of  soda^  or  Glauber  salt,  has  been  used  by 
some  manufacturers  in  place  of  soda  ash,  which  ought 
not  to  be  employed,  as  the  same  is  partly  converted 
into  sulphide  or  sulphuret  and  oxsulphite  of  sodium, 
which  is  detrimental. 

Fluorspar,  a fluoride  of  calcium,  may  be  added  to 
the  mixture  of  sand  and  alkali,  as  it  produces  a more 
fusible  silicate,  which  will  harden  soon  after  applica- 
tion by  the  affinity  for  this  alkali.  In  the  production 
of  hard  cements,  the  fluohydric  acid  is  of  great  service, 
for  it  assists  in  the  hardening  of  the  mortar,  and  form- 
ing a good,  permanent  cement. 

White  arsenic  in  powder,  [arsenious  acid,]  and 
nitrate  of  soda,  are  used  in  this  composition ; they 
produce  a white  soluble  glass ; while,  without  any 
admixture,  the  product  is  green.  From  three  to  eight 
per  cent,  of  either  is  used. 


THE  MANUFACTURE  OF  SOLUBLE  GLASS. 


I.  The  POTASH  SOLUBLE  GLASS. 

It  is  obtained  by  mixing  15  parts  powdered  quartz 
or  pure  sand  with  10  parts  purified  pearl  ashes,  and 
1 part  charcoal,  in  a Hessian  crucible,  and  exposing 
the  mixture  so  long  to  a heat  until  the  mass  after  six 
hours  has  become  vitrified.  Charcoal  is  employed  for 
assisting,  by  its  decomposition,  the  production  of  car- 
bonic  acid,  as  also  some  sulphuric  acid  which  may 
have  been  produced.  It  is  at  present,  however,  omit- 
ted, and  if  manufactured  on  a large  scale  the  vitrifi- 
cation is  done  rn  a reverberatory  furnace  capable  of 
holding  from  1,200  to  1,500  pounds.  The  ashes  and 
sand  must  be  Avell  mixed  together  for  some  time,  and 
the  furnace  must  be  very  hot  before  throwing  the  mix- 
ture in  it,  and  must  be  constantly  kept  up  until  the 
entire  mass  is  in  a liquid  condition..  The  tough  mass 
is  then  raked  out  and  thrown  upon  a stone  hearth  and 
left  to  cool.  The  glass  mass  so  obtained  appears  to  be 
hard  and  blistery,  of  blackish  gray  color,  and  if  the 
ashes  w^ere  not  quite  pure  it  will  also  be  adulterated 
with  foreign  salts.  By  pulverizing  and  exposing  it  to 
the  air  it  will  absorb  alkali,  and  by  degrees  the  foreign 
salts  will,  after  frequent  agitation  and  stirring,  be 
completely  separated,  particularly  after  pouring  over 
the  mass  some  cold  water,  which  dissolves  them,  but 
not  the  soluble  glass.  The  purified  mass  is  now  put 
into  an  iron  cauldron,  containing  five  times  the  quan- 


38 


MANUFACTURE  OF  SOLUBLE  GLASS. 


tity  of  hot  water,  in  small  portions,  and  with  constant 
agitation,  and  replacing  occasionally  hot  water  for  that 
which  evaporated  during  the  boiling,  and  after  five  or 
six  hours  the  entire  mass  is  dissolved  ; the  liquid  is 
removed  and  left  to  settle  over  night,  in  order  to  be 
able  to  separate  any  un  decomposed  si  lex.  The  next 
day  it  is  evaporated  still  more,  until  it  has  assumed  the 
consistency  of  a syrup,  and  standing  28°  B.,  and  is 
composed  of  28  per  cent,  potash,  62  per  cent,  silica  and 
12  per  cent,  water.  It  has  an  alkaline  taste,  and  is 
soluble  in  all  proportions  of  water,  and  is  precipitated 
by  alcohol,  and  if  any  salts  do  effervesce  they  may  be 
wiped  ofP.  The  color  is  not  quite  white,  but  assumes 
a greenish  or  yellowish, white  color. 

JI.  The  MANUFACTURE  OF  SODA  SOLUBLE  GLASS  : To 
45  parts  silica  or  white  river  sand  are  added  23  parts 
carbonate  of  soda  fully  calcined,  and  3 parts  charcoal, 
and  is  then  treated  in  the  same  manner  as  the  other 
glass.  The  proportions  of  the  mixture  are  altered  by 
the  different  manufacturers ; some  propose  to  100  parts 
silex,  60  parts  anhydrous  glauber  salt  and  15  to  20 
parts  charcoal.  By  the  addition  of  some  copper  scales 
to  the  mixture,  the  sulphur  will  be  separated.  Another 
method  is  proposed  by  dissolving  the  fine  silex  in  caus- 
tic soda  Ij^e.  Kuhlmann  employs  the  powdered  flint, 
which  is  dissolved  in  an  iron  cauldron  under  a pres- 
sure of  7 to  8 atmospheres.  According  to  Liebig  the 
infusorial  earth  is  recommended  in  place  of  sand,  on 
account  of  being  readily  soluble  in  caustic  lye,  and  he 
proposes  to  use  120  parts  infusorial  earth  to  75  parts 
caustic  soda,  from  which  240  parts  silica  jelly  rnaj^  be 
obtained.  His  mode  is  to  calcine  the  earth  so  as  to 
become  of  white  colors,  and  passing  it  through  sieves. 


MANUFACTURE  OF  SOLUBLE  GLASS. 


30 


The  lye  he  prepares  from  75  ounces  calcined  soda, 
dissolved  in  five  times  the  quantity  of  boiling  water, 
and  then  treated  by  56  ounces  of  dry  slacked  lime; 
this  lye  is  concentrated  by  boiling  down  to  48°  B.  ; 
in  this  boiling  lye  120  ounces  of  the  prepared  infu- 
sorial earth  are  added  degrees,  and  very  readily 
dissolved,  leaving  scarcely  any  sediment.  It  has  then 
to  undergo  several  operations  for  making  it  suitable 
for  use,  such  as  treating  again  with  lime  water,  boil- 
ing it,  and  separating  any  precipitate  formed  thereby, 
which,  b}^  continued  boiling,  forms  into  balls,  and 
which  can  then  be  separated  from  the  liquid.  This 
clear  liquid  is  then  evaporated  to  consistency  of  syrup, 
forms  a jelly  slightly  colored,  feels  dry  and  not  sticky, 
and  is  easily  soluble  in  boiling  w^ater. 

The  difference  between  potash  and  soda  soluble 
glass  is  not  material ; the  first  may  be  preferred  in 
white  washing  wdth  ])laster  of  Paris,  while  the  soda 
glass  is  more  fluidl}^  divisible. 

It  may  be  observed,  that  before  applying  either 
soluble  o’lass,  it  ought  to  be  exposed  to  the  air  for  ten 
to  twelve  days,  in  order  to  allow  an  efflorescence  of 
any  excess  of  alkali,  which  might  act  injuriously. 
There  are,  however,  many  methods  proposed  to  ob- 
viate this  difficulty,  and  which  will  be  mentioned 
hereafter. 

III.  The  DOUBLE  SOLUBLE  GLASS. 

This  is  a compound  of  potash  and  soda,  is  prepared 
from  100  parts  quartz,  28  parts  purified  pearl  ashes, 
22  parts  anhydrous  bicarbonate  of  soda,  6 parts  of 
charcoal,  which  are  spread  in  such  manner  as  already 
described.  If  the  mass  is  fully  evaporated  to  dryness, 
forms  a vitreous  solid  glass  which  cannot  be  scratched 


40 


MANUFACTURE  OF  SOLUBLE  GLASS. 


by  steel,  has  a conchoidal  fracture,  of  sea-green  color, 
translucent  and  even  transparent,  has  a specific  gravity 
of  1.43. 

lY.  The  SOLUBLE  glass,  after  Kaulbach,  for  the  use 
of  sterro-chromic  painting. 

It  is  obtained  by  fusing  3 parts  of  pure  carbonate  of 
soda  and  2 parts  powdered  quartz,  from  which  a con- 
centrated solution  is  prepared,  and  1 part  of  which  is 
then  added  to  4 parts  of  a concentrated  and  fully 
saturated  solution  of  potash  glass  solution,  by  which 
it  assumes  a more  condensed  amount  of  silica  with  the 
alkalies  ; and  which  solution  has  been  found  to  work 
well  for  paint.  Siemens’  patent  for  the  manufacture 
of  soluble  glass  consists  in  the  production  of  a liquid 
quartz^  by  digesting  the  sand  or  quartz  in  a steam 
boiler  tightly  closed,  and  at  a temperature  correspond- 
ing to  4-5  atmospheres,  with  the  common  caustic 
alkalies,  wdiich  are  hereby  capacitated  to  dissolve 
from  three  to  four  times  the  weight  of  silica  to  a thin 
liquid.  The  apparatus,  which  was  patented  in  1845, 
is  well  known  in  this  country  ; as  some  persons,  many 
years  later,  obtained  a patent  for  the  same  apparatus 
in  the  United  States,  which  on  inspection  does  not 
difler  from  that  of  Siemens  Brothers. 

Description  of  Siemens’  Apparatus  for  dissolving 
silica  in  soda  lye,  under  a pressure  of  five  atmos- 
pheres, or  sixty  pounds  to  the  square  inch  : 


APPARATUS  FOR  DISSOLVING  QUARTZ, 

TINDER  PRESSURE  OF  FIVE  ATMOSPHERES. 


H.E.PEASESC 


^fANIJFACTURE  OF  SOI.UBLE  GLASS. 


43 


The  whole  apparatus  consists  of  the  boiler  A and 
the  clissolvino;  kettle  B. 

Fig.  1 represents  the  front  side,  and  2 the  horizon- 
tal. A and  B are  connected  by  the  pipe  a.  The 
kettle  B is  constructed  of  two  strong  walls,  with  a 
space  h of  the  width  of  1-2  inches. 

The  steam  passes  through  the  pipe  a into  the  space 
h.  In  order  to  reach  the  inner  kettle,  which  is  per- 
fectly tight,  the  wall  c has  to  be  unscrewed.  Under 
the  middle  of  this  wall  the  box  d is  now  attached, 
which  encloses  the  iron  pipe  passing  through  the 
length  of  the  kettle.  Then  the  shovels,  or  agitators, 
ff^  are  now  applied  with  the  wheel  g at  the  end  for 
effecting  the  revolutionary  movement.  The  steam- 
cocks  A,  as  seen  at  the  front  wall  (?,  for  indicating  the 
stage  of  the  water  in  the  interior  kettle  ; the  cock  i 
serves  for  pumping  and  discharging  the  solution,  and 
the  cock  h for  letting  off  the  water,  which  was  con- 
densed in  the  steam  chamber  C. 

The  outer  kettle  is  surrounded  with  ashes,  or  any 
other  non-conducting  substance. 

The  boiler  is  supplied  with  ventils  and  manome- 
ters, and  the  kettle  B.  is  tested  to  stand  a pressure  of 
80-100  pounds  per  square  inch. 

The  kettle  is  now  filled  with  the  necessary  quantity 
of  silex,  after  the  front  wall  has  been  screwed  on  by 
means  of  the  cock  and  is  filled  up  with  the  caustic 
lye,  wdiich  is  composed  of  100  lbs.  carbonate  of  soda 
to  20  gallons  water,  and  1 lb.  of  silex  for  each  quart  of 
water;  wdien  filled,  and  the  steam  having  assumed 
the  tension  of  60  lbs.  to  the  square  inch,  as  indicated 
by  the  safety  ventil,  the  cock  m is  opened,  when  the 
steam  passes  to  the  other  kettle,  and  condenses  on  the 


44  MANUFACTURE  OF  SOLUBLE  GLASS. 

cold  wall  of  the  inner  kettle  ; here  the  temperature  is 
raised,  and  assumes  soon  a pressure  of  sixtj^  pounds, 
which  point  is  indicated  hj  the  escape  of  steam  from 
the  safety  valve.  Fire  is  now  kept  up  for  six  to  eight 
hours  under  a constant  escape  of  vapor. 

During  all  this  time  the  shovels  or  agitators  are 
kept  in  motion  by  the  workmen,  and  tlien  the  silex 
contained  in  the  kettle  will  have  dissolved  from  80-90 
per  cent.,  and  is  drawn  off,  and  may  be  re-filled  for  a 
new  operation. 

The  apparatus  may  undergo  some  modification  as 
the  agitators  get  a different  form,  etc.,  etc. 

The  silica  to  be  employed  is,  as  already  stated  to 
be,  the  common  sand,  which  is  at  first  calcined  and 
thrown  in  water;  when  dry,  it  is  ground  as  fine  as 
flour. 

The  liquid  silica  when  discharged  from  the  kettle 
may  be  evaporated  to  dryness,  when  it  assumes  a 
compact  mass,  a vitreous  and  conchoi-dal  fracture  and 
a hardness,  so  as  to  give  sparks  on  steel,  without  the 
brittleness  of  flint. 

The  solution  as  it  is  obtained  from  the  kettle  may 
be  converted  into  a white  fine  stone,  by  adding  fine 
sand,  until  it  assumes  a plastic  mass,  say  3-4  parts, 
with  the  addition  of  a little  chalk  or  lime  and  white 
clay  ; by  exposing  this  mass  when  formed  into  pressed 
stones  or  objects  to  the  atmosphere  for  some  time,  the 
stone  is  now  in  the  best  condition. 

Instead  of  fine  sand,  fine  powdered  dry  silicate  may 
be  substituted,  and  a better  stone  thereby  obtained. 

When  the  mass  is  dried,  it  must  undergo  the  pres- 
sure of  a hydraulic  press. 

The  addition  of  chloride  of  calcium  and  chloride  of 


MANUFACTURE  OF  SOLUBLE  GLASS. 


45 


iron,  either  in  liquid  state  or  in  dry  powders,  is 
highly  recommended  for  promoting  the  hardening 
process. 

Siemens’  remarks  of  the  application  of  the  silex 
liquid,  that  the  sand  to  be  employed  must  be  first 
calcined  and  then  thrown  into  cold  water,  and  after- 
wards ground  into  fine  powder,  which,  when  mixed 
with  his  liquid,  becomes  compact,  insoluble  and 
white,  possessing  a vitreous  and  conchoidal  fracture, 
and  a hardness  so  as  to  give  sparks  by  steel. 

The  same  gentleman  also  recommends  for  the  pro- 
duction of  a white  stone,  to  work  up  the  fine  silex 
with  so  much  liquid  soluble  glass  so  as  to  form  a 
plastic  mass,  say  from  3-4  parts  of  the  sand  may  be 
required,  similar  to  potter’s  clay,  and  adding,  at  the 
same  time,  a small  quantity  of  chalk  and  fine  clay, 
whereby  the  mass  becomes  more  uniform  and  com- 
pact. Prepared  in  this  manner,  objects  moulded  or 
pressed  from  the  mass  must  be  exposed  to  the  air  for 
some  time. 

For  monuments,  millstones  and  other  building  ma- 
terial, he  uses  1 part  liquid  silica  to  2 parts  fine  sand 
and  12  parts  coarse  sand,  which  mass,  formed  into  the 
desired  sizes  or  objects,  after  being  dried  long  enough 
in  the  air,  are  left  in  a heated  room  of  75°  for  several 
days,  and  even  to  the  boiling  point  of  water  ; they 
become  so  hard,  after  a lapse  of  four  to  six  days,  that 
they  never  crack  or  fall  to  pieces.  It  is  also  recom- 
mended to  expose  the  mass  to  the  pressure  of  a hy- 
draulic press  before  exposing  to  the  air.  For  obtain- 
ing a cement — roofing  and  wall  body — it  is  advisable 
to  add  the  chloride  of  calcium  to  the  mass,  and  thereby 
the  excess  of  alkali  is  absorbed. 

3* 


46 


MANUFACTURE  OF  SOLUBLE  GLASS. 


The  mass  so  formed  may  be  steeped  in  a solution 
of  chloride  of  calcium,  or  chloride  of  iron,  before 
exposing  to  the  atmosphere.  In  all  these  cases  the 
silica  ought  to  be  emploj^ed  very  concentrated,  even 
in  jelly  form. 

Tim  uses  of  the  soluble  glass  are  here  condensed  in 
a short  sketch,  intended  as  a circular  to  those  desirous 
of  obtaining  some  information  : 

“the  USES  OF  ^'SOLUBLE  GLASS  (lIQUID  SILEX,)  SILICATE 
OF  SODA,  SILICATE  OF  POTASH,  SILICATE  OF  SODA 
AND  POTASH  (combined.) 

“ Liquid  silica  is  now  employed  in  the  arts  for 
many  useful  purposes,  and  particularly  for  preserv- 
ing stone  buildings  from  decomposition  ; for  prepar- 
ing an  artificial  stone,  and  thereby  reducing  the  price 
of  building,  and  making  a composition  more  orna- 
mental. Its  introduction  for  architecture  is  but  of 
recent  date,  and  the  true  and  proper  method  of  appli- 
cation not  yet  on  an  infallible  base  ; but  the  subject 
is  of  so  vast  importance,  that  experiments  are  con- 
tinually going  on  for  making  a perfect  stone  from  its 
original  ingredients. 

“ The  cause  of  gradual  decomposition  of  building 
stone  is  attributed  to  the  expansion  and  contraction 
of  water  absorbed,  as  well  as  to  the  chemical  action 
of  carbonic  acid  of  the  atmosphere,  which  abstracts 
portions  of  the  gases  from  the  silicates,  and  liberat- 


* In  tlie  year  1832  Dr.  F.*prepared  a quantity  of  soluble  glass  for 
tlie  U.  S.  Government  to  preserve  the  cannon,  guns  and  bomb-sliells 
from  rust  or  oxydation  at  the  Navy  Yard  in  Brooklyn,  to  the  fullest 
satisfaction  of  the  late  Commodore  Perry. 


MANUFACTURE  OF  SOLUBLE  GLASS. 


47 


ing  thereby  silica.  Many  palaces  in  Europe,  churclies 
and  other  public  buildings,  have  been  retinished  by 
the  silicate,  such  as  the  Louvre  and  Notre  Dame  Ca- 
thedral in  Paris,  the  Houses  of  Parliament  in  London, 
and  in  other  cities.  Still,  its  general  application  has 
met  with  many  failures.  It  was  found  that  rain 
counteracted  the  effect  before  the  alkali  has  had  time 
to  take  up  a sufficient  quantity  of  carbonic  acid  from 
the  atmosphere  and  to  liberate  the  insoluble  silicate  ; 
the  coating  will  produce  cracks,  and  a gradual  disin- 
tegration of  the  surface  or  compound  is  caused  there- 
by. Numerous  remedies  were  suggested  to  counter- 
act this  evil — the  chloride  of  calcium,  oxychloride  of 
magnesium,  the  bittern  of  the  salines,  and  hydroflu- 
oric acid.  At  present,  a concrete  stone  of  considera- 
ble hardness  and  durability  is  now  prepared  by 
means  of  greater  pressure  and  proper  manipulation, 
the  main  object  being  to  neutralize  and  extract  the 
alkali,  and  to  form  a solid  chemical  compound  by  a 
second  aj)plication  of  a weak  wash  of  chloride  of 
calcium  or  magnesium.  The  object  is  now  fully 
achieved. 

“ Another  important  application  of  the  soluble  glass 
is  to  render  wood  non-inflammable,  and  stop  any 
communication  of  the  Are,  and  at  the  same  time 
proof  against  water  and  damp.  The  wood,  timber  or 
other  substances,  after  being  boiled  for  several  hours 
in  the  soluble  glass,  then  exposed  in  tanks,  contain- 
ing solution  of  lime  water  and  solutions  of  chloride 
calcium,  are  hereby  petrified. 

“ Rail-road  sleepers,  cross-ties,  house,  ship  and 
bridge  timber  will  also  be  silicified  by  this  process. 
Telegraph  poles  become  more  durable  and  better  non- 


48 


MANUFACTURE  OF  SOLUBLE  GLASS. 


conductors  of  electricity.  The  lining  of  barrels  for 
oil  and  other  liquids,  the  coating  of  tanks,  tubs  and 
cisterns,  flour  barrels,  to  prevent  the  flour  getting 
musty,  is  very  easily  and  efiectuall}^  done  by  the  proper 
and  judicious  use  of  the  liquid  silica. 

“ Soluble  glass  may  be  mixed  with  paper  pulp,  or 
cheap  vegetable  and  animal  fibre,  and  serve  for  the 
manufacture  of  a variety  of  useful  articles,  such  as 
boxes,  trunks,  soles  for  boots  and  shoes,  patterns, 
moulds  and  handles.  Invaluable  and  of  the  highest 
iisefulnessy  the  soluble  glass  can  he  employed  in  fire- 
proof  paints  ^ cements^  varnishes^  etc.^  for  which  pur- 
poses the  daily  demands  are  sufficient  proof  s. 

The  dentists  make  use  of  the^silica  for  mending 
their  plaster  moulds,  or  in  case  of  an  accident  to  the 
cast  of  a set  of  teeth.  Valuable  documents  are  made 
fireproof,  and  parchment  board,  slates  and  marbles  are 
cemented  together,  and  cracks  and  crevices  filled  up. 

“ The  woolgrowers  apply  the  silicate  of  soda  and 
potash  to  the  greatest  advantage  for  cleansing  or  de- 
greasing the  fleece  wool  and  make  it  soft. 

“ The  waste  of  wool  or  cotton  used  in  the  locomo- 
tive engines  to  sustain  the  lubricating  materials,  may 
be  cleaned  and  made  new  by  the  aid  of  soluble  glass. 

A hard  and  ornamental  cement,  which  can  be 
moulded  like  plaster  of  Paris,  is  obtained  from  the 
mixture  of  silicate  of  soda  and  ground  dolomite  or 
magnesian  limestone,  which  may  be  used  both  natural 
and  calcined  in  equal  quantities,  and  before  the  mass 
is  dry,  the  bittern  (chloride  of  magnesium)  from  the 
salines  is  added,  which  will  harden  it  at  once.  A 
good  cellar  and  roofing  cement  is  made  by  adding  to 
this  mass  three  parts  of  white  sand. 


MANUFACTURE  OF  SOLUBLE  GLASS. 


49 


“ The  silicate  is  also  used  for  penetrating  fire-brick 
and  clay,  in  order  to  make  them  more  fireproof,  and 
also  used  for  cementing  the  walls  ; for  producing  a 
durable  putty  in  iron  castings,  such  as  furnaces, 
heaters,  stoves,  etc.,  and  also  for  mending  air-holes. 
Boiler  makers  can  produce  a very  durable  lining  by 
making  a cement  of  silicate  with  asbestos  and  man- 
ganese finely  ground  ; it  renders  boilers  and  other 
metallic  vessels  perfectly  fireproof,  and  tlie  best  fire 
and  anti-rust  paint  for  iron,  steel  and  brass.  There 
are  a great  many  more  useful  applications  in  which 
the  silicate  may  be  used.” 

The  alkaline  silicates,  as  have  been  here  described, 
have  a bright  future  for  their  application  : the  genius 
of  the  nineteenth  century  cannot  fail  to  accomplish 
the  perfecting  the  work  begun  fifty  years  ago,  and  to 
this  moment  still  liable  to  faults.  Ere  long  we  will 
be  enabled  to  produce  an  artificial  stone  which  shall 
excel  nature;  we  will  be  able  to  produce  a perfect 
silicification  of  wood  and  other  organic  matter ; we 
will  challenge  the  atmosphere  and  other  chemical 
productions  to  do  their  best  for  forming  a decomposi- 
tion of  those  materials  obtained  by  the  new  acquired 
skill  to  resist  their  action.  The  labors  of  Fuchs,  Lie- 
big, Kuhlmann,  Yicat,  Fremy,  Guerin  and  Bansome 
have  fairly  begun  their  work,  and  in  ten  years  more 
the  sliipbuilder,  carpenter,  mason,  painter,  the  rail- 
road contractor  and  the  mechanic  in  general,  will 
consider  this  valuable  substance  indispensable. 

Among  the  most  simple  processes  in  the  silicifica- 
tion or  manufacture  of  artificial  stone  is  that  of  Kan- 
some,  which  consists  in  the  following  manner  : 


50 


MANUFACTURE  OF  SOLUBLE  GLASS. 


The  sand,  after  being  dried,  is  worked  up  in  a mill 
with  the  soluble  silicate  prepared  from  caustic  soda 
and  flints,  the  latter  being  dissolved  bj  the  former, 
and  evaporated  down  to  a specific  gravity  of  1,700. 
The  plastic  mass  thus  produced  is  obedient  to  the  will 
of  the  moulder,  and  can  be  manipulated  into  any 
form,  from  a cube  to  elaborate  screens,  from  a grind- 
stone to  an  exceedingly  chiseled  fountain.  The' 
mass  so  prepared  is  then  saturated  with  chloride  of 
calcium,  applied  simply  by  immersion  or  assisted  by 
the  action  of  an  air-pump,  in  either  process  the  so- 
lution being  gradually  heated  to  a temperature  of 
212°  F. 

The  indurating  action  of  the  chloride  of  calcium 
is  promoted  in  closed  chambers  connected  with  a 
steam  boiler.  When  this  has  been  carried  on  for  a 
sufficient  length  of  time,  by  opening  a cock  the  solu- 
,tion  is  forced  by  steam  pressure  into  a separate  cham- 
ber, leaving  the  stone  to  cool  gradually  in  partial 
vapor,  by  which  all  danger  of  cracking  is  avoided  ; 
a casualty  which  is  liable  to  happen  when  large 
masses  are  exposed  to  rapid  extremes  of  temperature 
in  the  open  air.  In  order  to  remove  or  extract  the 
soluble  salts  of  calcium  and  sodium  from  the  body 
of  the  stone,  which  is  effected  in  the  same  closed 
chambers  by  the  admission  of  steam,  or  steam  and 
water  alternately,  which,  as  it  condenses  and  becomes 
saturated  with  the  salts  referred  to,  is  returned  into 
the  boiler,  where  the  steam  is  generated,  and  the 
chloride  of  calcium  is  again  made  available  forfuture 
operations,  thus  obviating  the  serious  loss  incurred 
by  washing  the  stone  in  the  way  hitherto  adopted. 

Mr.  F.  was  led  to  his  last  experiments  from  the 


MANUFACTURE  OF  SOLUBLE  GLASS. 


51 


mauj  faults  which  lie  discovered  in  manipulating  ; 
he  supposed,  at  first,  that  by  mixing  sand  and  frag- 
ments of  stone  with  the  fluid  silicate  into  a kind  of 
paste  and  exposing  them  to  the  air,  they  would  be 
permanently  solid.  But  he  found  that  stones  they 
made  very  soon  became  disintegrated  in  any  moist 
atmosphere,  and  particularly  in  England,  and  could 
never  indurate.  To  remove  this  serious  objection,  he 
subjected  them  to  the  action  of  heat  in  a kiln,  and  he 
found  then  that  at  a brio-ht  red  the  cementino;  mate- 
rial  or  silicate  parted  with  some  of  its  free  alkali, 
the  portion  thus  renewed  combining  with  some  of 
the  sand  to  produce  an  insoluble  glass,  unaffected 
by  exposure  to  any  of  the  acids  present  in  the  air, 
and  not  cracking  by  exposure  to  frost  when  damp. 
This  artificial  stone  could  be  made  so  porous  as  to  be 
well  adapted  for  filtering  slabs,  or  it  could  be  so 
compacted  by  mechanical  pressure  before  burning  as 
to  yield  a material  not  inferior  in  its  power  to  resist 
atmospheric  action  and  even  absorption.  Paving 
slabs,  garden  vases,  balusters,  tombstones  and  various 
architectural  fixtures,  often  constructed  of  terra  cotta, 
were  produced  of  superior  quality  and  greater  dura- 
bility. The  stone  thus  made,  however,  after  some 
exposure,  was  found  to  become  unsightly,  owing  to 
the  efflorescence  of  the  saline  matter. 

This  patent  siliceous  stone  was  also  found  too  ex- 
pensive to  come  into  general  use  on  a large  scale,  but 
the  inventor  has,  at  last,  succeeded  in  reaching  to  a 
satisfactory  result. 

The  author  has,  many  years  ago  in  the  course  of 
his  experiments,  succeeded  in  preparing  an  artificial 
stone  in  the  following  manner  : — Eluorspar,  finely 


52 


MANUFACTURE  OF  SOLUBLE  GLASS. 


ground,  is  mixed  with  the  powdered  soluble  glass, 
2 parts  of  the  first  to  1 part  of  the  latter,  the  mixture 
made  into  a thin  paste  by  the  concentrated  liquid 
soluble  glass,  and  then  as  much  finely  powdered  shell 
limestone,  or  magnesian  limestone  added,  until  the 
mass  becomes  thick  enough  to  form  into  moulds  or 
blocks,  whichever  may  be  desired  ; after  an  expo- 
sure of  three  to  four  days  to  the  atmosphere,  are 
treated  by  a weak  solution  of  chloride  of  calcium,  (2 
pounds  dry  chloride  to  the  gallon  of  hot  water,) 
this  liquid  will  soon  be  absorbed  by  the  stone  ; it 
is  then  exposed  again  to  the  atmosphere  for  a week  ; 
a dilute  hydro-fiuoric  acid  is  then  applied  with  a 
sponge,  and  again  exposed  to  the  atmosphere ; after 
a lapse  of  a week  the  stone  is  as  hard  as  a natural 
stone,  and  not  liable  to  crack  or  to  disintegrate. 

This  composition  is  much  easier  prepared,  and  in- 
stead of  common  lime,  chalk  may  be  substituted,  and 
the  result  is  still  more  favorable.  Instead  of  the  en- 
tire quantity  of  lime,  coarse  sand  may  be  partially 
added,  and  after  the  stones  are  moulded,  are  exposed 
to  hydraulic  pressure,  and  then  exposed  to  the  air, 
previous  to  which  the  chloride  of  calcium  has  to  be 
thrown  over  it.  The  price  of  hydro-fluoric  acid,  as  is 
used  for  this  purpose,  costs  about  25  cents  per  pound, 
and  this  suffices  for  ten  square  feet. 

Furthermore  it  may  be  remarked,  that  exposing  the 
stone  so  prepared  may  be  subjected  to  a high  temper- 
ature or  not;  it  may  be  left  to  the  operator  to  de- 
cide whether  it  will  improve  the  stone  by  this  manipu- 
lation. 

For  the  sandstone  imitation,  when  1 part  liquid 
soluble  glass  is  to  be  mixed  with  2 parts  powdered 


MANUFACTURE  OF  SOLUBLE  GLASS. 


53 


soluble  glass,  and  15  parts  of  sand  is  added,  it  is  ne- 
cessary to  expose  the  mass  to  great  pressure,  but  re- 
quires not  the  addition  of  chloride  of  calcium,  while 
exposure  to  great  heat  is  indispensable. 

An  artificial  stone  may  be  also  obtained  by  the  use 
of  the  alkaline  silicates  with  common  chalk,  which,  by 
mixing  even  cold  with  the  liquid  silica,  is  at  oncecon- 
Yerted  into  silicate  of  lime  and  carbonate  of  soda  or 
potash  ; this  composition,  when  exposed  to  the  air,  be- 
comes in  a few  days  hard  enough  so  as  to  resemble  a 
hydraulic  lime,  to  adhere,  when  wetted  again,  like  a 
cement,  which  may  be  used  for  restoring  ci’acks  and 
crevices  in  marble  works  and  monuments. 

The  silicification  of  chalk  has  led  to  numerous  ex- 
periments, and  resulted  in  the  production  of  artificial 
stone,  in  the  formation  of  hydraulic  lime,  hydraulic 
mortar  and  the  various  cements.  The  first  successful 
result  of  the  treatment  of  chalk  with  the  silicate  solu- 
tion has  shown  that  the  hardening  of  the  chalk  ex- 
tended to  the  depth  of  four  inches,  which  not  alone 
was  produced  from  the  decomposition  of  the  silicate 
by  the  carbonate  of  lime,  (chalk,)  but  also  by  the  car- 
bonic acid  of  the  atmosphere.  If  two  balls  of  chalk 
of  equal  size  and  quality  are  silicified  at  the  same 
time,  and  one  of  them  is  exposed  to  the  atmosphere, 
the  other  kept  under  a bell  glass,  where  the  carbonic 
acid  of  the  atmosphere  is  withdrawn,  the  first  will  ac- 
quire more  hardness  than  the  other,  which  proves  that 
the  silicification  has  assumed  a hydrate  of  silico — car- 
bonate of  lime — which  loses  by  degrees  its  water  of 
crystalization,  and  forming  a precipitate  of  silica, 
contributing  mainly  to  the  hardening  of  the  stone. 

A hydraulio  lime  may  be  obtained  by  the  mixture 


54 


MANUFACTURE  OF  SOLUBLE  GLASS. 


of  a fat  or  rich  limestone  combined  witli  soluble  glass 
in  a dry  state,  say  10  parts  silicate  to  100  parts  of  air 
lime,  both  fine  powder,  which  proves  plainly  the 
theory  of  the  part  which  the  silicates  play  in  the  pro- 
duction of  the  native  limestone,  the  artificial  hydrau- 
lic lime,  mortar,  cements,  and  the  application  of  all 
silicates  for  the  purposes  of  building,  production  of 
artificial  stones,  and  the  conversion  of  organic  into  in- 
organic materials,  as  we  shall  show  hereafter. 

Wagner’s  report  on  soluble  glass  is  in  the  follow- 
ing lines  : 

Soluble  glass,  called  also  water  glass,  liquid  quartz, 
liquid  silex,  silicate  of  soda  or  potash,  w’as  accidentally 
discovered  by  the  late  Professor  Fuchs,  of  Munich,  in 
the  year  181S,  in  the  course  of  some  investigations  he 
was  making  for  the  preparation  of  pure  silica.  He 
became  more  familiar  with  its  properties  in  1820,  and 
learned  how  to  prepare  it  by  the  solution  of  silica  in 
caustic  potash.  Afterward  he  studied  the  subject 
thoroughly,  and  became  acquainted  with  all  its  pro- 
perties and  uses.  In  the  year  1823,  as  the  theatre  in 
Munich,  which  had  been  destroyed  by  fire,  entailing 
great  loss  of  life  and  property,  was  rebuilding,  the 
Government  requested  a scientific  commission  to 
search  for  an  accent  that  would  render  the  wood-work 
and  stage  materials  incombustible.  Professor  Fuchs, 
in  association  with  Doctor  Pettenkofer,  at  once  in- 
stituted numerous  experiments  upon  soluble  glass  as 
the  best  agent  for  this  purpose,  and  the  conclusions  at 
which  they  arrived  have  been  fully  confirmed  by  the 
subsequent  studies  and  experience  of  other  men.  In 


MANUFACTURE  OF  SOLUBLE  GLASS. 


55 


182G  soluble  glass  was  raauufactured  in  Augsburg  on 
a large  scale,  and  sold  at  the  rate  of  25  florins  the  llO 
pounds.  From  this  time  forward  a knowledge  of  the 
new  compound  became  disseminated,  and  new  uses 
were  constantlj^  suggested  for  it. 

According  to  Professor  Fuchs,  there  are  four  kinds 
of  soluble  glass  : 

1.  Potash  glass. 

2.  Soda  glass. 

3.  Potash  and  soda  glass  (combined.) 

4.  Glazing  glass. 

Potash  Soluble  glass  is  prepared  bj  fusing  together  : 
45  pounds  of  quartz, 

30  pounds  of  potash, 

3 pounds  of  charcoal  in  powder,  and  digesting  the 
fused  and  pulverized  mass  in  water. 

Soda  soluble  is  coiiiposed  of: 

45  pounds  quartz, 

23  pounds  calcined  soda, 

3 pounds  charcoal ; 

Or,  according  to  Buchner,  more  economically  of : 
100  pounds  quartz. 

Go  pounds  calcined  glauber  salt, 

15  to  20  pounds  coal. 

There  are  several  ways  of  making  the  third  variety 
of  combined  soda  and  potash  soluble  glass.  J^y  fusing 
seignette  salt  (tartrate  of  potash  and  soda)  with  quartz; 
by  employing  equal  ecjuivalents  of  nitre  or  Chili  salt- 
petre and  quartz;  fusing  cream  of  tartar.  Chili  nitre 
and  quartz ; or  by  melting  at  once : 


56 


MANUFACTUKE  OF  SOLUBLE  GLASS. 


100  pounds  quartz, 

28  pounds  purified  potash, 

22  pounds  calcined  soda, 

6 pounds  charcoal  powder. 

For  technical  application  it  is  possible  to  mix  three 
volumes  of  a concentrated  potash  glass  solution  and 
two  volumes  of  a soda  glass  solution. 

The  fourth  variety,  called  glazing  or  fixing  glass,  is 
made  by  mixing  perfectly  saturated  potash  glass  with 
soda  glass,  and  is  used  for  producing  fast  colors  in 
stereochromy  or  fresco  painting. 

There  is  also  a wet  way  for  the  manufacture  of  solu- 
ble glass,  which  consists  in  dissolving  fiint  stones  in 
concentrated  soda  lye  in  iron  boilers  under  7 or  8 at- 
mospheres of  pressure,  and  for  this  purpose  infusorial 
silica  or  tripoli  is  also  specially  adapted.  The  tripoli 
is  first  calcined  to  destroy  all  organic  matter,  and  then 
introduced  into  boiling  soda  lye  of  1.5  specific  gravity, 
or  potash  lye  of  1.135,  and  afterward  clarified  by  a 
little  water  lime  and  evaporated  to  the  required  con- 
sistency. As  soluble  glass  readily  absorbs  carbonic 
acid,  it  must  be  kept  in  closely  stopped  packages. 
The  strength  of  the  solution  is  estimated  in  degrees 
founded  upon  the  package  of  dry  powder  dissolved  in 
the  water  ; 33°  means  33  parts  dry  glass  and  67  parts 
water;  40°  = 60  parts  water  and  40  parts  soluble 
glass.  In  applying  the  solution  to  wood-work,  roofs, 
fabrics,  porous  stones,  &c.,  it  is  necessary  to  begin 
with  a weak  solution  and  to  wait  until  it  is  thoroughly 
dry  before  putting  on  a second  coat.  The  second 
application  can  be  considerably  more  concentrated 
than  the  first.  It  will  not  adhere  to  freshly  painted 


MANUTACTCTEE  OF  SOLUBLE  GLASS.  5T 

surfaces,  but  when  the  oil  is  thoroughly  dry  and 
changed  in  tlie  sun  light,  the  water  glass  can  be  used 
with  impunity.  Care  must  be  observed  to  wash  out 
the  brush  thoroughly  after  use  to  prevent  its  harden- 
ing to  stone.  Soluble  glass  protects  wood  from  the 
influence  of  fire,  water  and  the  atmosphere.  The 
surface  of  wood  is  covered  with  glass,  and  not  only  will 
not  take  fire,  but  is  less  liable  to  decay.  Some  varie- 
ties of  wood  are  apt  to  be  discolored  by  the  solution  ; 
oak  and  beech  are  the  least  affected.  As  the  soluble 
glass  when  applied  to  wood  serves  a purpose  analo- 
gous to  a varnished  surface,  it  is  necessary  to  avoid  a 
too  concentrated  liquid,  as  otherwise  it  is  liable  to 
scale  off.  One  pound  of  33°  solution,  diluted  with  five 
pounds  of  water,  is  found  to  cover  wood  very  well. 
Wood,  paper,  linen  and  straw,  wdien  covered  with 
several  coats  of  soluble  glass,  are  no  longer  inflamma- 
ble, but  simply  char  when  exposed  to  fire.  A coating 
of  glass  also  prevents  the  decay  and  rotting  of  wood, 
and  keeps  out  worms.  Beer  barrels,  butter  firkins 
and  milk  tubs  can  be  easily  kept  clean  when  painted 
with  soluble  glass,  and  the  same  is  true  of  vessels  de- 
signed to  hold  sugars,  syrups,  wines,  petroleum,  &c. 
The  most  important  use  of  soluble  glass  is  its  applica- 
tion to  surfaces  of  stone  and  mortar.  For  this  purpose 
it  is  necessary  to  impregnate  the  surface  witli  a solu- 
tion composed  of  one  part  33°  and  three  parts  rain 
water.  For  this  purpose  a powerful  pump  or  syringe, 
with  a spout  like  a watering-pot,  is  used  for  injecting 
the  liquid,  in  the  form  of  syrup,  into  the  pores  of  the 
stone  or  mortar.  The  surfaces  thus  prepared  are  in 
condition  to  receive  the  further  coating  of  liquid 
quartz. 


58 


MANUFACTURE  OF  SOLUBLE  GLASS. 


Mortar  and  porous  limestones  react  upon  the  soluble 
glass,  producing  carbonate  of  lime,  hydrate  of  lime, 
and,  ultimately,  silicate  of  lime,  which  thus  presents 
an  impervious,  vitreous  surface,  capable  of  resisting 
the  action  of  moisture  and  the  atmosphere,  and  is  in 
a proper  state  for  fresco  painting  in  mineral  colors. 
Organic  colors  are  apt  to  be  destroj^ed  by  the  alkali 
of  the  soluble  glass,  and  hence,  for  fresco  painting, 
mineral  paints  are  alone  available.  A second  coating 
of  paint,  rubbed  up  with  soluble  glass,  is  usually  suffi- 
cient for  all  practical  purposes,  and  a wall  thus  treated 
can  be  washed  with  soap  and  water,  and  kept  tho- 
roughly clean.  A plain,  white  color  is  obtained  by 
mixing  chalk  with  soluble  glass.  Zinc  white,  and  sili- 
cate of  soda  set  so  rapidly,  that  it  is  necessary  to  add  J 
to  -J-  its  weight  of  precipitated  sulphate  of  baryta  be- 
fore applying  the  color.  Baryta  white  and  soluble 
glass  also  afford  a good,  fast  color.  Fluor  spar,  with 
pulverized  glass  and  soluble  glass,  also  gives  an  ex- 
ceedingly solid  mass.  The  pigments  that  have  been 
found  by  experience  to  serve  the  best  purpose  are 
chromate  ot  zinc,  sulphate  of  cadmium,  blue  and  green 
ultramarine,  Schweinfurth  green,  oxide  of  chromium, 
cinnabar,  &c.  Prussian  blue  and  colors  prepared  from 
it,  and  chromate  of  lead,  will  not  answer,  as  they  are 
destroyed  by  the  alkali,  the  same  as  organic  colors. 
It  is  well  known  that  the  fresco  paifiting  in  the  capi- 
tal at  Washington,  in  the  new  museums  in  Berlin  and 
Munich,  are  done  with  water  glass,  and  that  the  suc- 
cess in  their  use  is  complete. 

Soluble  glass,  with  or  without  colors,  adheres  closely 
to  such  metals  as  iron,  zinc  and  brass,  and  protects 
them  from  the  influences  of  the  air  and  water.  It  has 


MANUFACTURE  OF  SOLUBLE  GLASS. 


59 


been  found  that  when  stoves  are  painted  with  a mix- 
ture of  solubie  glass  and  black  oxide  of  manganese,  a 
species  of  flux  is  produced  by  the  heat  which  does  not 
scale  off,  but  thoroughly  protects  the  iron  from  any 
corroding  action.  Plate  glass,  when  coated  with  the 
soluble  silicate,  becomes  opaque,  and  when  baryta  is 
mixed  with  the  liquid  quartz,  it  assumes  a fine,  white 
appearance.  If  the  glass  be  heated  it  becomes  en- 
ameled, like  porcelain  ; and  fixed  colors,  such  as  ultra- 
marine  and  oxide  of  chromium,  open  up  an  extensive 
application  for  soluble  glass  for  transparencies,  church 
windows,  &c.  The  manufacture  of  artificial  building 
stone  by  means  of  soluble  glass  has  been  conducted  in 
Germany  and  England  on  an  extensive  scale.  In  Yi- 
enna  barracks  of  an  enormous  size  have  been  con- 
structed of  such  artificial  stone;  and  the  tower  of  the 
Cathedral  in  that  city  was  put  into  thorough  repair  in 
the  only  way  that  was  possible,  considering  the  great 
height  of  the  tower  and  the  extent  to  which  it  had 
fallen  to  decay. 

When  ground  chalk  or  marble  is  stirred  into  a paste 
with  soluble  glass,  the  mass  becomes  so  hard  that  it 
can  be  employed  for  building  purposes,  or  for  the 
restoration  of  decayed  stone  structures. 

Marble  and  dolomite  immersed  in  a solution  of 
soluble  glass,  and  the  operation  repeated  a number  of 
times,  take  up  an  appreciable  quantity  of  silica,  and 
become  so  liard  that  they  are  capable  of  taking  a 
fine  polish.  Attempts  to  employ  such  stones  for 
lithography  have  been  made,  but  not  altogether  with 
success.  Artificial  stone  can  be  prepared  as  follows  : 

AYell  washed  and  gently  heated  sand  is  stirred  into 
a warm  solution  of  soluble  glass  until  a proper  con- 


60 


MANUFACTURE  OF  SOLUBLE  GLASS. 


sistoDce  has  been  reached  for  pouring  it  into  a mould. 
After  it  has  set  it  is  removed  from  the  frame,  which 
ought  to  have  been  previously  oiled,  and  is  left  to  dry 
in  an  airy  place.  To  avoid  too  great  a consumption 
of  water  glass,  a stone  or  brick  can  be  put  in  the  centre 
of  the  mould.  It  is  also  possible  to  stir  in  pebbles  and' 
to  use  earthy  colors  in  imitation  of  marble  and  con- 
glomerate. Such  artificial  material  becomes  very 
hard,  and  is  adapted  to  pavements,  hearths  and  build- 
ing purposes. 

Soluble  glass  can  be  used  in  the  manufacture  of 
paper  hangings,  for  printing  on  paper  and  woven 
fabrics,  for  attaching  gold  and  silver  powder  to  any 
kind  of  object. 

Hydraulic  lime  can  be  prepared  by  mixing  in  fine 
powder  10  to  12  parts  by  weight  of  dry  soluble  glass 
and  100  parts  of  lime — this  affords  a ready  way  of 
preparing  a hydraulic  cement  from  ordinary  lime, 
which  is  always  available. 

One  of  the  earliest  and  best  known  uses  of  soluble 
glass  is  as  a cement  for  glass,  porcelain  and  metals. 
It  is  put  up  in  small  packages  for  this  purpose,  and 
sold  on  the  corners  of  streets  under  various  names. 
Pieces  of  glass  or  porcelain  cemented  in  this  way  will 
break  more  readily  in  places  which  were  whole,  than 
where  they  were  repaired.  The  solution  ought  to  be 
quite  concentrated  when  employed  for  this  purpose. 
The  fragments  to  be  repaired  must  be  heated  to  the 
boiling  point  of  water,  and  both  surfaces  be  then 
moistened  with  the  cement  and  pressed  closely  to- 
gether, and  held  in  position  by  a strong  cord,  and  left 
to  dry  in  a warm  place.  By  mixing  sulphate  of  mag- 
nesia or  calcined  magnesia  and  soluble  glass,  a cement 


MANUFACTURE  OF  SOLUBLE  GLASS. 


61 


can  be  formed  that  can  be  cast  into  moulds,  and  very 
generally  be  substituted  for  meerschaum. 

Soluble  glass  has  been  used  in  restoring  several 
European  churches,  also  the  Houses  of  Parliament  in 
London. 

Wood  and  timber  and  other  porous  substances,  after 
being  boiled  for  several  hours  in  soluble  glass,  then 
exposed  in  tanks  containing  lime  water  or  chloride  of 
calcium,  and  left  to  dry,  become  highly  vitrified  and 
incombustible.  Pail-road  ties,  ships’  timber,  house 
and  bridge  beams,  have  been  treated  in  this  manner 
with  entire  success. 

The  silicate  is  also  used  for  penetrating  fire  brick 
and  clay,  and  for  cementing  the  walls  of  furnaces. 

When  stirred  up  with  chloride  of  calcium  and  used 
for  luting  down  the  covers  of  crucibles,  it  answers  an 
excellent  purpose. 


4 


HYDRAULIC  LIMESTONE,  CEMENTS  AND 
PLASTERS. 

It  is  necessary  to  explain  the  main  material  used 
in  building,  which  is  lime,  before  we  can  proceed 
further  with  our  subject  of  silicification,  or  imitation 
of  the  same  substances  by  means  of  art,  latterly  ac- 
quired, and  which  bids  fair  to  excel  nature.  From 
one  of  Ansted’s  lectures  on  practical  geology,  the 
lollowing  article  on  cements  and  plasters  gives  a good 
idea  of  their  importance  : 

“ The  earliest  architectural  constructions  to  fasten 
together  the  bricks  or  stones  of  which  buildings  are 
made  were  of  various  kinds  ; the  most  common  is 
called  mortar.  It  is  obtained  by  first  calcining  crude 
limestone  in  a kiln,  and  converting  it  into  quicklime, 
by  depriving  it  of  its  carbonic  acid.  After  calcining,  the 
resulting  quicklime  is  of  a whitish  or  grayish  pow- 
dery and  cracked  substance,  which,  on  the  application 
of  water,  absorbs  a certain  quantity  with  the  evolu- 
tion of  much  heat,  and  crumbles  into  a fine  powder. 
This  powder,  further  moistened,  made  into  a thin 
paste  with  water,  and  mixed  with  two  or  three  times 
its  own  weight  of  sharp  sand,  is  called  mortar.  Slaked 
lime,  or  hydrate  of  lime,  as  moistened  quicklime  is 
called,  absorbs  carbonic  acid  from  the  air,  and  in  time 
mortar  is  reconverted  into  limestone  ; but  the  opera- 
tion goes  on  under  peculiar  conditions,  and  the  result 


HYDRAULIC  LIMESTONE,  CEMENTS,  ETC. 


63 


is  also  peculiar ; for  a film  of  silicate  of  lime  is  formed 
round  each  grain  of  sand,  and  thus  the  whole  mass 
and  the  stones,  between  which  it  is  placed,  become  in 
time  more  compact  than  tlie  particles  of  limestone. 

As,  however,  there  are  different  kinds  of  lime- 
stone, more  or  less  impure,  the  result  will  be  limes  of 
very  different  qualities  and  properties.  These  re- 
quire special  treatment  to  obtain  from  tliem  the  best 
results.  The  purest  carbonate  of  lime,  such  as  mar- 
ble, or  chalk,  make  what  is  called  a rich  lime,  setting 
firmly  only  in  dry  air,  while  the  very  impure  car- 
bonates, in  which  clay  is  largely  mixed  w’ith  the  lime- 
stone, result  in  the  production  of  hydraulic  limes, 
which  set  more  or  less  rapidly  in  moist  air  or  even 
under  water.  Some  of  the  impure  limestones  are 
used  in  the  manufacture  of  cements  by  the  admixture 
of  definite  proportions  of  foreign  ingredients.  Some- 
times, by  the  admixture  of  certain  substances  (as  puz- 
zuolana)  with  the  rich  limes,  instead  of  sand,  hydraulic 
limes  are  produced.  There  are  few  subjects  con- 
nected with  the  application  of  geology  that  are  more 
important,  than  the  determination  of  the  material  that 
should  be  used  and  the  treatment  adopted  in  various 
countries  in  the  manufacture  of  cements,  mortars  and 
stuccoes. 

“ Commencing  with  nearly  pure  carbonates  of  lime, 
it  is  not  difficult  to  trace  the  changes  that  take  place 
in  their  conversion  into  cements f a layer  of  such 
mortar,  not  too  thick,  placed  between  bricks  or  stone, 
which  are  themselves  absorbent,  and  kept  in  dry  air, 
dries  gradually  and  holds  together  such  substances 
with  extraordinary  tenacity.  But  this  is  a work  of 
years,  and  sometimes  even  centuries  must  run  out 


G4  HYDEAULIO  LIMESTONE, 

before  the  extreme  of  hardness  is  attained  ! It  is  not 
nnnsual  to  find  imperfectly  hardened  mortars  in  very 
old  constructions.  The  mortar  that  fastened  together 
the  bricks  in  the  old  Roman  walls  is  now  almost 
everywhere  so  far  hardened  that  a fracture  takes  place 
in  the  brick  rather  than  in  the  cement. 

‘‘  Limestone  is  widely  distributed,  and  almost  every 
variety,  however  impure,  can  be  burnt  into  lime.  In 
the  manufacture  of  good  common  mortar  to  set  in 
the  air,  pure  limestones  and  those  of  fair  ordinary 
quality  are  available  ; but  in  using  them,  attention 
must  be  given  to  their  composition  and  even  texture  ; 
thus,  the  hardest  limestones  and  marbles  make  the 
fattest  lime,  but  each  variety  yields  a lime  of  dififerent 
quality,  distinct  in  color,  in  weight,  in  the  greediness 
with  which  it  absorbs  water,  and  in  its  ultimate  hard- 
ness. The  method  of  calcination  also  varies,  but  the 
general  result  is  that,  after  burning  the  limestone,  the 
resulting  quicklime  is  lighter  than  the  original  stone, 
and  differs  from  it  essentially.  To  determine  the  na- 
ture of  lime  and  its  peculiar  properties,  perfectlj^  fresh 
samples  should  be  placed  in  a small  open  basket  and 
immersed  in  pure  water  for  five  or  six  seconds  ; re- 
moved from  the  water,  the  loose,  unabsorbed  water 
must  be  allowed  to  run  oflF,  and  the  contents  of  the 
basket  emptied  into  a stone  or  iron  mortar.  Accord- 
ing to  the  nature  of  the  limestone,  the  lime  will  now 
exhibit  some  one  the  following  phenomena : 

“1.  It  will  hiss,  crackle,  swell,  give  off  much  va- 
por, and  fall  into  powder  instantly. 

“2.  It  will  remain  inert  for  some  short  time,  not 


CEMENTS,  ETC.  G5 

exceeding  five  or  six  minutes,  after  which  the  results 
stated  in  (1)  will  be  energetically  declared. 

“ 3.  It  will  remain  inert  for  more  than  five  minutes, 
sometimes  extending  to  a quarter  of  an  hour;  it  then 
gives  off  vapors  to  a moderate  extent,  and  cracks 
without  noise  and  without  much  evolution  of  heat. 

“ 4.  The  lime  will  crack  without  noise  and  with 
little  steam,  but  not  until  an  hour  has  elapsed. 

5.  The  lime  will  become  scarcely  warm  to  the 
touch,  will  not  fall  to  powder,  and  will  crack  to  a very 
small  extent. 

‘‘  In  each  case,  before  the  effervescence  (if  any  takes 
place)  has  quite  disappeared,  the  slaking  should  be 
completed  by  the  addition  of  water,  not  thrown  upon 
the  lime,  but  by  the  side  of  it,  and  the  result  should 
be  frequently  stirred,  more  water  be  added,  till  the 
whole  is  brought  to  the  consistence  of  thick  paste. 
When  the  mass  has  cooled,  which  will  not  take  place 
for  two  or  three  hours,  the  whole  should  be  beaten  up 
again,  until  a firm  but  tenaceous  paste  is  produced, 
resembling  clay  prepared  for  pottery  manufacture. 
Vessels  being  then  filled  with  tliis  paste,  or  obtained 
from  each  variety  of  limestone,  the  day  and  hour  of 
immersion  should  be  marked  upon  them,  after  which 
they  are  left  to  solidify. 

“ We  thus  obtain  a test  of  the  nature  of  the  materi- 
als used,  which  may  belong  to  one  of  five  classes  : 

(1.)  Rich  limes. 

(2.)  Poor  limes. 

(3.)  Moderately  hydraulic  limes. 

(4.)  Hydraulic  limes. 

(5.)  Eminently  hydraulic  limes. 


66  HYDKAULIC  LIMESTONE, 

“ The  word  hydraulic,  as  applied  to  lime,  means 
only,  that  it  possesses  the  property  of  setting,  or  be- 
coming solid,  in  moist  air  or  under  water. 

“ Rich  limes  are  obtained  from  the  purest  and 
hardest  limestones.  When  slaked,  they  increase  to 
double  their  volume;  if  employed  alone,  they  remain 
unaltered  even  for  years,  and  they  are  soluble  in  pure 
water.  Limestones  which  contain  from  1 to  6 per  cent, 
of  foreign  substances,  such  as  silica,  alumina,  magne- 
sia, &c.,  yield  rich  limes;  but  such  as  contain  from 
15  to  30  per  cent.,  are  poor  limes;  they  increase  in 
bulk,  but  little  on  slaking,  do  not  set  under  water, 
and  are  soluble,  like  the  rich  limes,  except  that  they 
leave  a residuum.  The  fossiliferous  limestones  make 
bad  mortar,  as  the  slaking  is  irregular ; limestones 
containing  much  silica  swell  in  setting,  and  may 
dislocate  the  masonry  executed  with  them.  Where 
alumina  is  in  excess,  the  lime  is  apt  to  shrink  and 
crack.  Where  carbonate  of  magnesia  is  combined 
with  carbonate  of  lime,  as  in  the  magnesian  lime- 
stones, the  original  bulk  is  retained.  For  ordinary 
purposes,  moderately  puie  limestones,  with  a mixture 
of  foreign  substances,  is  a moderately  pure  limestone. 
Hydraulic  limes  are  of  great  value  in  construction,  and 
are  extremely  interesting,  and  are  either  obtained 
naturally  from  the  burning  of  certain  varieties  of  cal- 
careous rock,  or  are  manufactured  artiticially  by  mix- 
ing limestones  with  the  requisite  foreign  ingredients; 
such  are  the  Roman  cement,  Portland  cement,  Park- 
er’s and  Rosendale  cements.  The  Portland  cement  is 
largely  manufactured  at.  the  mouth  of  the  Thames 
from  a mixed  river  mud,  while  Roman  cement  is 


67 


CEMENTS,  ETC. 

formed  from  the  nodules  found  in  the  cliffs  near  Har- 
wich, all  owing  their  quality  to  argillaceous  admix- 
ture. Limestone,  containing  from  15  to  25  per  cent, 
of  a silicate  of  alumina,  will  burn  into  a good  hy- 
draulic lime.  It  is  also  quite  certain  that  the  oxide  of 
iron  and  carbonate  of  magnesia  exercise  a great  influ- 
ence in  rendering  limes  more  hydraulic.  All  materi- 
als intended  for  the  manufacture  of  cements  require 
to  be  burnt  carefully,  and  ground  down  to  a fine  pow- 
der, and  the  best  cement  is  the  lightest.  When 
these  cements  are  intended  for  the  production  of  an 
artificial  stone,  from  ten  to  twelve  times  the  weight  of 
broken  stones  and  pebbles  are  added,  and  form  also 
an  excellent  concrete.  A stone  made  from  these  ce- 
ments just  described,  will  bear  a strain  varying  from 
20-60  pounds  to  the  square  inch. 

“ The  plaster  cement  is  obtained  from  the  gypsum,  or 
sulphate  of  lime,  abundant  in  England,  France  and 
the  United  States;  is  treated  like  common  limestone 
for  a cement.  The  calcining  of  gypsum  does  not  in- 
volve its  decomposition,  but  the  water  of  solidification 
being  driven  off  by  the  calcination,  leaves  only  a soft 
white  powder  called  plaster  of  Paris  ; when  this  is 
again  united  with  water,  the  latter  is  absorbed,  and 
the  mass  becomes  first,  plastic,  and  then  solid  ; but 
it  cannot  be  brought  back  to  its  original  condition  as 
a crystaline  mineral,  but  it  is  converted  into  various 
substances  used  as  cement,  such  as  Keene'' s cement, 
if  alum  is  added  to  the  fine  powdered  plaster  ; parian 
cement,  if  borax  is  used  ; Martin’s  cement,  if  pearl 
ashes  are  employed.  Stucco  is  a very  useful  material 
for  ornaments  for  in  and  out-door  work,  is  nothin£r 


68  HTDKAULIC  LIMESTONE, 

else  but  a plaster  of  Paris,  finely  ground,  and  a weak 
glue  added  before  mixing  it  with  water. 

‘‘One  of  the  richest  kinds  of  hydraulic  lime  may  be 
obtained  from  volcanic  minerals  mixed  with  limes ; 
such  material  is  the  Puzzuolana,  found  near  JNaples, 
as  well  as  other  substances  found  in  large  quantities 
in  the  neighborhood  of  extinct  volcanic  districts,  as  in 
France  and  on  the  Khine ; and  which,  according  to 
its  chemical  analysis,  consists  of  M per  cent,  of  silica, 
15  per  cent,  alumina,  87  per  cent,  lime,  4 per  cent, 
magnesia,  and  12  per  cent,  oxide  of  iron  ; combined 
with  lime  instead  of  sand,  have  the  property  of  render- 
ing even  the  richest  limes  hydraulic,  and  fit  for  use  for 
every  description  of  works  executed  in  the  sea  or  in 
fresh  water ; they  have  been  used  from  time  imme- 
morial with  great  success,  and  may  be  mixed  either 
with  fat  or  hydraulic  limes  and  silicate  of  soda  to  form 
a plastic  mass,  and  assist  in  the  setting  of  the  lime. 

“In  regard  to  hydraulic  cements,  Fremy  says  that 
the  setting  of  cements  is  due  to  two  different  chemical 
actions  : 1.  To  the  hydration  of  the  alurninates  of  lime, 
and  2.  To  puzzuolanic  action,  in  which  the  hydrates 
of  lime  combine  with  the  silicates  of  lime  and  alumina. 
He  found  that  alumina  is  even  a better  flux  for  lime 
than  silica,  and  he  suggests  that  the  very  basic  com- 
pounds of  these  two  substances,  those,  for  instance, 
containing  from  80  to  90  per  cent,  of  lime,  may  be 
-useful  in  the  iron  furnace  for  absorbing  sulphur  and 
phosphorus,  and  free  the  metal  from  those  noxious  im- 
purities; and  he  finds  that  no  substance  is  capable  of 
acting  as  a puzzuolana  except  the  simple  or  double 
silicates  of  lime,  containing  only  from  30-40  per  cent, 
silicate,  and  sufficiently  basic  to  form  a gelatinous  pre- 


69 


CEMENTS,  ETC. 

cipitate  with  acid ; and  he  confirms  Yicat’s  theory, 
that  the  cause  of  the  setting  of  hydraulic  cements  was 
owins:  to  the  formation  of  a double  silicate  of  alumina 

o 

and  lime  absorbing  waters,  forming  hydrates  and  caus- 
ing the  settino*  of  the  materials.  * 

o o 

“ Theory  of  Hydraulicity. 

“ Fremy  has  lately  published  his  researches  on  hy- 
draulic cements,  and  in  giving  the  theory  of  their  hy- 
draulicity, he  rejects  the  commonly  received  opinion 
that  the  setting  of  hydraulic  cement  is  due  to  the  hy- 
dration of  the  silicate  of  lime  or  that  of  double  silicate 
of  alumina  and  lime.  These  salts  form  no  combina- 
tion whatever.  He  attributes  the  setting  of  hydraulic 
lime  to  two  chemical  actions  : 1st.  To  the  hydration 
of  the  aluminate  of  lime ; 2d.  To  the  reaction  of  hy- 
drate of  lime  upon  the  silicate  of  lime,  and  the  silicate 
of  alumina  and  lime  which  exist  in  all  cements,  and 
in  this  case  act  as  puzzuolanas. 

“ The  calcination  of  the  argillaceous  limestone  pro- 
duces good  hydraulic  cement  only  when  the  propor- 
tions of  clay  and  lime  are  such  that  they  form,  in  the 
first  place,  an  aluminate  of  lime,  represented  by  one 
of  the  following  formulse  : A1  O3,  Ca  O — Als,  O3,  2 Ca 
O ; — AI2,  O3,  3 Ca  O ; in  the  second  place  a very  sim- 
ple or  multiple  silicate  of  lime,  which  gelatinizes  with 
acids,  and  approximates  to  the  following  formnlge: — 
Si  O3,  2 Ca  O — Si  O3,  3 Ca  0 ; and  thirdly,  free  lime, 
wliich  may  act  upon  the  preceding  puzzuolanic  sili- 
cates. 

“ In  many  cases  the  chemical  composition  of  an 
argillaceous  limestone  is  not  only  the  condition  which 

4^- 


TO 


HYDEAULIC  LIMESTONE, 


determines  the  quality  of  the  cement ; the  reaction  of 
the  lime  upon  the  clay  must  take  place  at  the  highest 
temperature.  Indeed,  this  excessive  heat  produces 
the  hydraulic  elements  of  the  cement  in  the  basic 
conditions  which  the  setting  in  the  water  requires, 
and  which,  by  melting  the  aluminate  of  lime,  gives  it 
all  its  activity. 

“ Hydraulicity  of  Magnesia  Hydrates. 

“ Since  the  publication  of  Fremy’s  paper,  Deville 
has  read  a note  before  the  Academy  of  Sciences,  ‘ On 
the  Hydraulicity  of  Magnesia,’  in  which  he  alludes 
to  a specimen  of  magnesia  prepared  by  the  calcination 
of  the  chloride  sent  to  him,  seven  years  before,  by  M. 
Donny.  A portion  of  it  was  left  under  the  tap  of  his 
laboratory,  constantly  exposed  to  running  water.  In 
time  it  took  a remarkable  consistence,  became  hard 
enough  to  scratch  marble,  and  was  clear  as  alabaster. 
After  six  years  exposure  to  the  air,  it  has  not  per- 
ceptibly changed,  and  its  analysis  gave  the  following 
results:  Water,  27.7  per  cent.;  carbonic  acid,  8.3; 
alumina  and  oxide  of  iron,  1.3;  magnesia,  57.1 ; sand, 
5.6.  Total,  100. 

“ Thus  the  substance  appeared  to  be  essentially  a 
crystalized  hydrate  of  magnesia,  like  brucite,  which 
does  not  absorb  carbonic  acid.  To  prove  that  it  was 
really  so,  M.  Deville  prepared  magnesia  by  calcinihg 
the  nitrate,  powdered  it,  made  it  into  a plastic  mass, 
and  sealed  in  a tube  with  some  boiled  distilled  water. 
After  some  weeks  the  mass  became  as  hard  and  com- 
pact as  the  other,  and  also  crystaline  and  translucid. 
After  drying  in  the  air,  this  mass  was  found  to  con- 


71 


CEMENTS,  ETC. 

sist  of  30.7  per  cent,  water,  and  69.3  per  cent,  mag- 
nesia, showing  it  to  be  a simple  hydrate  of  magnesia. 
With  similar  hydrate,  cast  of  medals  were  taken, 
which,  on  being  placed  in  water,  assumed  the  appear- 
ance of  marble. 

M.  Balard’s  magnesia,  prepared  by  calcining  the 
chloride,  obtained  by  treatment  of  sea  water,  when 
brought  to  a red  heat  shows  astonishing  hydraulic 
qualities,  which  are  partially  destroyed  by  calcining 
at  a white  heat.  A mixture  of  chalk  or  marble  and 
magnesia,  in  equal  parts,  forms  a plastic  mass,  which, 
placed  under  water  for  some  time,  becomes  hydrated 
and  extremely  hard. 

An  average  sample  of  Portland  cement  will  yield, 
upon  analysis,  in  one  hundred  p'arts  : Lime,  fifty-five  ; 
iron,  seven  ; alumina,  eight ; silica,  twenty-four  ; pot- 
ash and  soda,  three ; sand,  two ; water,  one.  The 
essential  constituents  are  the  lime,  alumina  and  silica.” 
The  author  delivered  a discourse  on  cements  before 
the  Polytechnic  Association,  20th  April,  1866,  of  which 
the  following  is  the  substance  : 

Cements. 

“ The  subject  for  the  evening — cements — was  here 
taken  up,  when  Dr.  Lewis  Feuchtwanger  exhibited  a 
number  of  minerals  used  in  difterent  kinds  of  cements, 
and  read  the  following  paper  : 

“ ‘ The  meaning  of  cement  is,  a paste  used  for  unit- 
ing solid  surfaces  without  always  forming  a combina- 
tion with  the  constituents  of  either  surface.  Many 
cements  contain  pulverulent  substances  which  are 
mingled  with  a glutinous  or  very  adhesive  material, 


72 


HYDRAULIC  LIMESTONE, 


and  do  not  combine  chemically ; others  again  form 
chemical  combinations.  Furthermore,  many  substan- 
ces are  capable  of  assuming  a liquid  or  semi-fluid  form, 
and  are  thus  applied  between  the  surfaces  of  bodies 
which  are  firmly  united  when  the  fluid  has  solidified. 

“ ‘ The  most  common  cements  are  mortar  and  hy- 
draulic cement.  We  have  also  lutes  and  fire  cements  ; 
but  as  it  is  important  to  ascertain  the  best  mode  of 
obtaining  a good  hydraulic  cement,  that  is,  a cement 
which  hardens  under  water,  I will  at  once  take  up  this 
brancli  of  the  subject,  premising,  however,  that  com- 
mon mortar  is  simply  a mixture  of  lime,  water  and 
sand,  the  best  proportions  being  one  cubic  foot  of  fresh 
burnt  lime,  weighing  about  thirty-five  pounds,  and 
three  and  one-half  cubic  feet  of  good  river  sand,  not 
round,  but  angular ; these,  with  one  and  one-half 
cubic  feet  of  water,  produce  about  three  and  one-half 
cubic  feet  of  good  mortar. 

‘ Hydraulic  or  Homan  cement  is  composed  of  cer- 
tain proportions  of  lime,  sand,  clay  and  water  ; after 
it  has  been  applied  a few  days,  and  placed  underwater, 
it  becomes  very  hard  and  like  stone.  We  now  find 
walls  and  piers  which  are  known  to  have  been  built 
more  than  a hundred  years  ago,  and  have  been  exposed 
under  water,  to  have  remained  as  solid  as  iron.  The 
name  Homan  cement  is  derived  from  the  district  of 
Puzzuoli,  near  JSTaples,  where  the  natural  material, 
the  tufas  and  puzzuolanas,  are  in  great  abundance. 
The  Pontine  marshes  around  Home  and  the  volcanic 
tufas  near  Naples  have  always  afibrded  a natural 
cement,  for  they  are  composed  of  silica,  alumina  and 
lime.  Besides  these  tufas,  many  marls,  belonging  to 
tlie  sedimentary  rocks,  are  used  as  hydraulic  cement. 


CEMENTS,  ETC. 


73 


The  cement  stones,  allied  to  the  oolitic  formation,  and 
found  in  argillaceous  strata  alternating  with  limestone 
beds,  and  of  very  curious  nodular  and  lenticular  forms 
and  concretions,  on  the  English  and  French  coasts, 
and  in  this  country  the  septaria,  toadstones,  Indus  hel- 
montii  of  various  sizes,  and  consisting  of  siliceous  clay 
and  lime  strata  interwoven,  yield  the  proper  material 
for  hydraulic  cement.  All  these  marls  contain,  ac- 
cording to  analysis,  about  seventy  per  cent,  of  car- 
bonate of  lime,  twenty  per  cent,  of  silica,  and  twenty 
per  cent,  of  clay ; and  the  lime  when  calcined  becomes 
caustic,  and,  in  combination  with  silica,  forms,  under 
water,  a chemical  compound,  as  a hydrated  silicate  of 
lime  ; and,  by  the  presence  of  clay,  which  is  a silicate 
of  alumina,  forms  double  silicates  of  greater  solidity. 
Ca  O— CO2— Si  0,—A],  O3. 

‘ The  Eoman  or  hydraulic  cement  mostly  con- 
tains, also,  magnesia  and  iron  ; whether  of  any  essen- 
tial benefit  or  not,  has  not  been  fairly  tested.  It  is 
certain  that  neither  of  these  substances  exercise  a 
pernicious  influence,  for  the  reason  that  dolomite,  a 
magnesian  limestone  found  in  great  abundance  in  this 
country,  offers  a fine  material  when  calcined  with  any 
marls,  so  abundant  along  our  coast.  It  produces  an 
excellent  hydraulic  cement. 

“ ‘ Tlie  analysis  of  the  hydraulic  lime  from  E-ondout, 
on  the  JSTorth  Eiver,  gites  in  one  hundred  parts  : 


Carbonic  acid, 35 

Magnesia, 12 

Alumina, 10 


Lime, 26 

Silica, 15 

Iron, 2 


“ ‘ Sand  or  quartz,  which  by  itself  is  unfit  for  a 
mortar,  when  calcined  with  lime,  becomes  very  suit- 


74  HYDRAULIC  LIMESTONE, 

able  for  a hydraulic  cement  or  artificial  stone,  for  it 
forms  a silicate  of  lime.  More  than  thirty  years  ago, 
1 entertained  the  idea  of  preserving  timber  by  the 
infiltration  of  silicate  of  lime  into  the  cells  of  planks, 
timber,  and  through  the  double  chemical  affinity  of 
silicate  of  soda  and  sulphate  of  lime.  The  experi- 
ments I made  then,  in  the  Brooklyn  Navy  Yard,  with 
pier  piles  and  wooden  vats,  were  very  satisfactory. 

“ ‘ For  water-proofing  cellars  and  buildings,  not 
alone  the  best  hydraulic,  but  other  cements  have  of 
late  years  been  introduced  in  this  city  ; for  instance, 
the  asphalt  cement,  which  is  very  extensively  em- 
ployed in  the  foundation  of  buildings.  Having  made, 
myself,  many  experiments,  for  a number  ofyears  past, 
in  order  to  introduce  the  silica  cement,  or  the  soluble 
glass  in  combination  with  alkaline  earths  as  a base, 
and  met  with  varied  success,  I beg  to  ofier  here  a 
sample  of  a cement  which  consists  of  silicate  of  lime 
combined  with  manganese  and  fiuorspar,  or  fiuoride 
of  calcium,  which  becomes  very  hard,  and  which,  I 
think,  will,  after  some  improvement  in  the  prepara- 
tion, be  found  highly  useful  in  keeping  dry  walls  and 
cellars.  I have  mixed  equal  quantities  of  manganese, 
limestone,  fluorspar  and  dry  soluble  glass,  and  make 
the  whole  mass  plastic  by  the  liquid  soluble  glass,  and 
apply  it  while  soft ; after  the  lapse  of  a few  hours  it 
becomes  very  hard.  ’ 

u 4 Yire  cements  are  lutes,  for  crevices  and  joints, 
which  are  intended  to  be  used  for  furnaces,  iron  pipes 
and  retorts  exposed  to  constant  red  and  white  heat; 
or  for  joining  gas  and  water  pipes,  and  many  other 
substances,  may,  if  judiciously  applied,  prove  very  ac- 
ceptable. I beg  to  offer  a few  which  I consider  useful : 


CEMENTS,  ETC. 


75 


‘‘‘No.  1.  Iron  Cement  or  Lute. — Erick  dust  and 
fire  clay  in  equal  parts,  borax,  red  lead  and  sal  am- 
moniac, one-tenth  of  the  other  ingredients  ; cast  iron 
turnings.  The  whole  mixture  made  up  with  water  so 
as  to  knead  them  together,  and  spread  it  in  layers. 
It  is  suitable  for  crevices  or  joints  of  iron  pipes,  fur- 
nace doors,  man  holes  of  boilers,  etc. 

“ ‘ No.  2.  A Steam-resisting  Cement. — Twm  parts 
litharge,  one  part  sand,  one  part  slaked  lime  ; made 
plastic  with  hot  glue. 

“ ‘ No.  3.  An  Iron  Cement — Manganese  twenty- 
four  parts,  red  lead  five  parts  ; formed  into  a paste 
w'ith  linseed  oil. 

“ ‘No.  4.  Cement  for  Fastening  Iron  and  Stone.— 
Calcined  plaster,  iron  filings  and  hot  glue. 

The  three  following  are  good  cements  for  cisterns, 
etc.: 


“ ‘ 1st.  Ten  parts  of  plaster  of  Paris,  two  of  Glauber 
salts,  four  of  clay,  and  four  of  lime. 

“ ‘ 2d.  Twenty-two  parts  of  clay,  nine  of  iron 
filings,  sixtj^-three  of  lime,  one  of  magnesia,  one  of 
pearl  ash  and  ten  of  charcoal. 

“ ‘ 3d.  Thirt}^  parts  of  sand,  seventy  of  lime,  three 
of  litharge,  made  up  with  linseed  oil. 

“‘A  very  remarkable  cement  for  almost  any  sub- 
stance is  made  in  the  following  manner:  Either  glue 
or  gelatine  is  swelled  up  in  water  and  then  immersed 
in  linseed  oil  and  heated.  It  dissolves  and  forms  a 
paste  of  great  tenacity,  which,  when  dry,  resists 
dampness  perfectly.  Two  pieces  of  wood  joined  by 
it  may  separate  anywhere  except  at  the  joint. 


76  HYDKAULIO  LIMESTONE, 

“ ‘The  china  or  diamond  cement,  for  joining  glass 
or  china  ware,  consists  of  gum  mastic  and  ammonia 
dissolved  in  alcohol,  to  which  is  added  hot  glue. 
Spalding’s  glue  is  the  old  Berzelius  paste,  that  is, 
glue  dissolved  in  acetic  acid.  The  Japanese  cement 
is  rice  flour  made  into  a paste  and  dried. 

“ ‘ In  1 811,  a patent  for  a lime  cement  was  obtained 
bj  Kulilmann,  who  adds  an  alkali,  like  soda  or  pot- 
ash, before  calcining  the  limestone  with  sand  and  clay, 
so  as  to  produce  a soluble  silicate  with  the  ingredients 
of  hydraulic  cement. 

“ ' The  Portland  stone  or  cement,  so  extensively 
used  in  England,  and  exported  largely  from  there  to 
all  parts  of  the  globe,  and  forming  the  base  of  many 
patent  cements,  such  as  Beese’s  and  others,  is  nothing 
but  powdered  oolite,  a mineral  lime  deposit.  Harne- 
lin’s  mastic  cement,  another  very  celebrated  cement, 
is  prepared  from  sixty-two  parts  of  oolite,  thirty-five 
of  sand,  and  three  of  litharge. 

“ ‘ The  celebrated  French  cement  of  Bouilly  is  said 
to  be  prepared  from  the  Boulogne  pebbles,  called  go- 
lets,  which  are  marly  nodules  of  all  sizes,  like  the  sep- 
tarias  and  marly  concretions  of  other  countries.  A 
number  of  years  ago  I prepared  a good  hj^draulic  ce- 
ment from  one  part  of  the  poorest  limestone,  one  of 
clay  and  three  of  sand.  I also  prepared  a terra  cotta, 
which  is  likewise  a cement,  composed  of  clay  and 
sand,  slowly  dried  and  calcined. 

“‘Among  the  great  variety  of  cements  .in  which 
silica  is  the  active  principal,  the  two  following  are 
very  useful ; 

“ ‘ 1.  A mortar,  to  be  made  as  hard  as  any  cement. 


77 


CEMENTS,  ETC. 

and  which  does  not  crack  in  setting,  and  even  of 
great  usefulness  as  hydraulic  cement  under  water,  is 
obtained  by  mixing  finely  slaked  lime  with  fine 
sand  (the  angular  grains  are  always  preferable  to  the 
round  grains  for  producing  a good  mortar.)  By  mix- 
ing the  sand  thus  prepared  with  finely  powdered 
quicklime,  and  stir  the  mixture  thoroughly.  During 
the  process  the  mass  heats,  and  may  then  be  em- 
ployed as  mortar,  to  which  has  to  be  added  to  one- 
eighth  of  the  mass  the  liquid  silicate  of  soda. 

“ ‘ One  part  of  good  slaked  lime  was  used  with  three 
parts  of  sand,  and  to  this  was  added  three-fourths  of 
its  weight  of  finely  powdered  quicklime ; the  mortar 
containing  one-eighth  of  the  liquid  silicate  of  soda  was 
then  used  as  a foundation  wall,  and  in  four  days  had 
become  so  hard  that  a piece  of  sharp  iron  would  not 
attack  it ; and  in  two  months  afterwards  it  had  be- 
come as  hard  as  the  stones  of  the  wall. 

“ ‘ 2.  A thin  coating  of  slaked  lime  made  into  paste 
with  water  or  whitewash  is  put  at  once  on  the  stone, 
and  before  becoming  quite  dry  apply  the  silicate  so- 
lution over  the  paste,  by  which  the  mass  becomes 
completely  insoluble  ; a petrification  takes  place  if  ap- 
plied to  vegetable  substances,  decomposition  is  pre- 
vented, porous  building  stone  and  brick  are  protected 
against  air  and  damp. 

“ ‘ Common  Moktar. 

“ ‘ Limestone,  an  impure  carbonate  of  lime,  when 
exposed  to  a red  heat,  loses  carbonic  acid  gas,  and  the 
oxide  of  calcium  or  lime  remains.  This  process  of 
burning  lime,  as  it  is  called,  is  accelerated  by  the 


78 


HYDEAULIO  LIMESTONE, 


presence  of  moisture  in  the  stone,  or  by  the  introduc- 
tion of  a small  quantity  of  steam  into  the  lime  kiln. 
The  hydrate  of  lime  reacts  with  considerable  power 
on  siliceous  compounds,  but  the  action  only  takes 
place  at  the  surfaces,  and  unless  the  lime  is  used  in 
very  thin  layers,  between  smooth  stones,  it  still  re- 
tains, in  the  centre  of  the  layer,  its  own  soft  and  fria- 
ble condition. 

“ ‘In  order  to  make  the  hydrate  of  lime  effective 
as  a cement,  it  is  mixed  with  sand,  one  of  the  most 
abundant  of  natural  compounds,  now  regarded  as  con- 
sisting of  two_atoms  of  oxygen  and  one  of  silicon. 
Equal  parts  of  tine  and  coarse  sand  are  said  to  be 
better  than  either  quality  used  separately  with  lime. 
Mortar  designed  for  exterior  or  surface  work  is  gen- 
erally made  with  fine  sand.  When  lime  is  compara- 
tively free  from  impurities,  and  crumbles  to  a tine 
powder  on  being  slaked,  it  is  called  fat  lime,  and  will 
require  about  six  times  its  own  weight  of  sand,  or,  if 
estimated  by  bulk,  one  cubic  foot  of  semi-tiuid  lime 
and  water,  called  the  milk  of  lime,  will  require  about 
three  or  four  cubic  feet  of  sand.  This  mortar  is  very 
effective  as  a cement  when  well  dried  or  set,  but  if  it 
is  placed  in  water,  the  lime  is  gradually  dissolved  and 
the  mass  is  disintegrated. 

• a c Hydraulic  Cement. 

“ ‘ For  all  permanent  structures  under  water  it  is, 
therefore,  essential  to  use  a material  called  hydraulic 
cement,  which  is  a mixture  of  lime  with  other  oxides 
possessing  the  valuable  quality  of  hardening  until  it 
has  the  solidity  and  permanency  of  the  masses  of  rock 


CEMENTS,  ETC. 


79 


bound  together  bj  it.  The  varieties  of  limestone  from 
wliich  hydraulic  cement  is  made,  wlien  burned,  yield 
a lime  tliat  is  very  slowly  slaked.  All  that  is  required 
is  to  add  water  until  it  attains  the  consistency  of 
dough  ; it  will  then  harden  and  become  concrete. 
These  hydraulic  limes  may  be  made  artiticially  by 
mixing  with  impure  slaked  lime  a quantity  of  burnt 
clay  in  the  proper  proportions’.  The  celebrated  Ro- 
man cement  is  a porous  volcanic  rock  found  at 
Puzzuoli,  near  Naples,  and  called  there  puzzuolana. 
It  consists  of  silicate  of  alumina,  soda  and  lime. 
This  substance  is  pulverized  and  mixed  with  common 
lime.’  ” 

The  Silicate  Hydraulic  Cement  in  the  Preven- 
tion OF  Wall-Damp. 

In  laying  the  foundation  of  any  building,  the  mat- 
ter of  particular  consideration  should  be  the  thorough 
drainage  of  the  site,  and  next  to  that  complete  pre- 
vention of  wall-damp,  that  is,  the  rising  of  moisture 
bj’  capillary  attraction  or  otherwise,  in  the  heart  of 
the  brick  or  stone  wmrk,  the  particulars  of  which 
have  been  lately  described  in  the  Manufacturer  and 
Buildeds  Journal^  to  which  the  author  had  added 
the  silicification  of  the  bricks  and  plaster.  It  states 
that  wherever  brickwork  comes  in  contact  with  the 
earth,  or  even  with  adjacent  walls  which  may  happen 
to  be  damp,  there  the  infection  is  certain  to  take,  and 
there  is  no  easy  cure  for  it,  if  once  it  makes  an  en- 
trance. 

The  readiest  remedy  in  all  cases  is  a layer  of  fine 
concrete,  which  may  be  thinly  coated  on  the  top  with 


80  IIYDEAULIG  LIMESTONE, 

asphaltum  laid  on  hot.  This  done  all  around  the  top 
of  the  walls,  external  and  internal,  the  piers  and  every 
piece  of  brickwork,  that  in  any  manner  has  connec- 
tion with  the  ground,  then  the  bricks,  which  ought 
to  be  specially  prepared  before  calcination  with  a 
silicate  solution,  should  be  heated  over  charcoal  fur- 
naces and  dipped  in  the  asphaltum  before  being 
laid.  It  is  evident  that  a preventive  course  could 
thus  be  formed  above  ground  at  a trifling  expense, 
wholly  impervious  to  wall-damp,  at  the  same  time 
giving  a base  to  the  superstructure  of  a quality  very 
far  superior  to  any  now  in  use.  Coating  the  outside 
face  of  the  wall  with  water-proof  silicated  cement,  as 
has  been  before  noticed,  is  the  only  safeguard  against 
capillary  attraction  from  below,  and  excluding  the  ex- 
ternal air  which  might  let  the  artificial  heat  of  the 
rooms  to  attract  the  enemy  of  wall-damp.  It  is  known 
that  common  brick  will  absorb  one-fifth  of  its  weight 
of  water,  and  where  the  storm  drives  the  rain  con- 
tinually against  the  face  of  a wall  for  a sufficient  time 
to  permit  the  interior  heat  to  attract  it,  the  inside  of 
the  wall  must,  of  necessity,  be  damp,  and  the  papering 
become  mouldy,  as  well  as  the  ceiling,  will  next  be 
rotten.  This  cause  of  wall-damp  is  one  that  cannot 
be  too  carefully  guarded  against,  as  it  is  one  to  which 
may  be  referred  the  early  decay  of  many  residences, 
as  well  as  the  inception  of  these  pulmonary  symptoms 
which  so  surely  steal  away  the  health  and  ultimately 
the  life  of  many  a victim. 

The  mortar  to  be  used  in  the  foundation  and  the 
wall  ought  to  be  very  well  prepared,  so  as  to  possess 
all  the  hydraulic  properties  and  silicification,  and  cau- 
tion should  be  taken  in  not  using  sea  sand,  which  will 


CEMENTS,  ETC. 


81 


certainly  create  the  damp  by  absorbing  all  the  water 
in  the  atmosphere,  this  being  the  chemical  effect  of  its 
saline  property. 

The  surface  of  the  walls  of  the  rooms  must  be  well 
attended  to  ; the  plaster  of  Paris,  which  is  generally 
employed,  ought  to  be  properly  silicified,  so  as  to  pre- 
vent the  absorption  of  the  natural  damp  of  the  atmos- 
phere created  in  uninhabited  and  unheated  rooms. 

It  is  preferable  to  paint  rooms  than  to  paper  them, 
for  the  white  lead  and  linseed  oil,  with  some  manganese 
to  facilitate  the  drying,  becomes  hard  after  a short 
time,  and  assists  tiie  fresh  plaster  wall  in  preventing 
the  admission  of  the  moisture,  as  the  fourth  coating  of 
Avhite  lead  is  applied  witli  equal  proportions  of  oil  and 
spirits  of  turpentine,  which  has  the  property  of  being 
very  volatile,  will  evaporate  entirely,  leaving  the  sur- 
face of  the  paint  of  a very  compact  and  hard  nature, 
and  rendering  the  plaster  incapable  of  absorption. 

Damp  Walls  and  Cellars. 

The  application  of  silicates  for  preventing  the  pene- 
tration of  rain  or  moisture  in  houses,  whereby  the 
■walls  are  absorbing  the  same,  and  render  the  paper- 
hangings  or  delicate  paint  unfit,  so  as  to  destroy  their 
appearance,  has  been  amply  and  satisfactorily  proved. 
The  silicates  of  soda  and  potash,  or  either  of  them,  are 
mixed  with  pure  wdiite  lead  or  zinc,-  and  applied  soon 
after  upon  the  walls,  which  will  dry  immediately. 

The  presence  of  damp  in  walls  arises  from  three 
causes  : either  from  the  porous  condition  of  the  mate- 
rials of  which  they  are  built,  allowing  the  penetration 
of  damp  from  without ; from  the  existence  of  salts  in 


82  HYDBAtJLIC  LIMESTONE, 

the  mortar,  bricks  or  stone,  which  absorb  and  give  out 
moisture,  according  to  the  changes  of  the  weather,  or 
from  damp  foundations.  The  first  only  can  be  reme- 
died by  the  application  of  external  coatings,  the  second 
by  battening  the  walls,  and  the  last  by  removing  the 
adjacent  earth  from  the  foundations. 

As  has  already  been  stated,  a single  application 
of  a paint  formed  with  lead  or  zinc  has  proved  very 
successful.  The  second  application  is  the  silicate  so- 
lution with  china  clay,  or  pure  alumina,  which  has 
the  advantage  of  not  drying  so  quick  as  that  with  lead 
or  zinc.  In  all  cases  the  j^aints  must  be  put  on  uni- 
formly, so  that  the  whole  wall  surface  should  be  com- 
pletely covered  with  the  solid  coat;  and  in  order  to 
effect  this,  a rough  stucco  surface,  from  two  to  three 
coats,  may  be  required.  It  is  found  also  useful  to 
apply  the  second  coat  thinner  than  the  first. 

The  mixture  of  liquid  silicate  of  soda  with  clay  and 
that  of  whiting,  or  washed  carbonate  of  lime,  may 
probably  be  the  most  reliable  for  keeping  out  damp 
from  walls  as  well  as  cellars. 

On  applying  the  lead  or  zinc  as  the  first  coat,  either 
of  them  or  both,  it  may  be  done  in  the  following 
manner  : 

Mix  them  with  a little  water  and  lay  them  on  the 
stone,  they  will  dry  very  soon  ; apply  then  the  silicate 
solution  by  means  of  a syringe.  If  the  application  is 
to  be  made  on  stone  which  shows  some  decay,  it  is 
necessary  to  remove  first  the  same,  apply  then  the 
aluminous  silicate  of  soda,  (by  an  equal  mixture  of 
liquid  silicate  with  fine  white  clay,)  and  then  apply 
the  carbonate  lime  and  silicate  wash  with  an  ordinary 
paint  brush,  stippling  it  so  as  to  give  it  the  appear-  • 


CEMENTS,  ETC. 


83 


ance  of  tlie  granulated  surface  of  tlie  stone.  "When 
dry,  it  will  adhere  sufficiently  to  allow  of  other  washes 
of  silicates  beino;  brushed  on  it. 

The  conditions  necessary  for  success  are: 

1.  The  wall  should  be  coated  with  a porous  mate- 
rial,  such  as  lime  or  Portland  cement. 

2.  The  coating  must  be  perfect.  A M^all  which  has 
been  once  painted  is  altogether  unfit  for  any  applica- 
tion of  siliceous  washes,  for  the  reason  that  it  is  not 
absorbent  enough. 

The  best  ground  for  any  siliceous  work  is  lime  and 
sand.  In  new  buildings  it  would  be  better  to  use 
lime  and  sand  at  once,  and  then  to  cover  it  with  lime 
and  silicate  of  alumina  and  soda.  The  precipitated 
sulphate  of  baryta  maj^  safely  be  applied  in  the  sili- 
cate of  soda  for  all  the  above  purposes,  and  it  will  pro- 
duce a good  coating  and  a fine  paint. 


MANUFACTURI5  OF  PORTLAND  CeMENT. 

Portland  cement  w^as  introduced  to  public  notice 
under  a patent  by  an  Englishman  nearly  fifty  years 
ago,  and  a partial  monopoly  in  its  production  has 
been  kej)t  up,  inasmuch  as  inexhaustible  beds  of  the 
raw  material  from  which  it  is  made,  and  an  abundant 
supply  of  fuel  necessary  for  their  economical  manu- 
facture, is  at  hand.  It  is  strange  that  under  these  con- 
ditions French  engineers  should  have  obtained  the  start 
of  their  professional  confreres^  and  that  they  should 
have  been  the  first  to  demonstrate  by  experiments,  and 
subsequently  by  the  erection  ot  magnificent  harbor 
works  on  their  seaboard,  the  valuable  properties  of  this 


84: 


HYDEAULIC  LIMESTONE, 


excellent  constructive  material.  We  may  date  the  ex- 
tensive  employment  of  Portland  cement  in  England 
from  the  commencement  of  the  metropolitan  main- 
drainage  works.  During  the  last  fifteen  years  the 
manufacture  of  Portland  cement  has  gone  on  steadily 
increasing,  until  at  the  present  day  we  find  that  little 
short  of  400,000  tons  per  annum  are  made  in  the 
county  ofXent — the  centre  of  cement  manufacture — 
irrespective  of  the  productions  of  many  minor  factories 
in  different  parts  of  the  country. 

The  chemistry  of  the  setting  of  Portland  cement  is 
by  no  means  so  well  understood  as  it  ought  to  be. 
There  is  no  doubt,  however,  that,  like  the  hydraulic 
lime  and  natural  cements,  it  is,  chemically  speaking, 
a double  silicate  of  lime  and  alumina  ; silicic  acid  is 
generated  by  the  hydration  of  the  cement,  and  forms 
insoluble  salts  with  the  lime  and  alumina  bases.  It  is 
a curious  fact  that  Portland  cement  hardens  more 
rapidly  when  salt  water  is  employed.  According  to 
Schweitzer,  1,000  grains  of  sea-water  in  the  English 
Channel  contains  27,060  grains  of  chloride  of  sodium  ; 
soluble  silica  has  a known  preference  for  alkaline 
bases,  and  it  is  not  improbable,  when  the  cement  is 
hydrated  with  sea- water,  that  the  chloride  of  sodium 
is  decomposed,  the  silicic  acid  of  the  cement  com- 
bining with  the  sodium  and  oxygen' of  the  water,  and 
forming  thereby  a silicate  of  soda,  or  a species  of  crude 
glass. 

Portland  cement  is  of  two  classes,  which,  for  the 
sake  of  distinction,  may  be  termed  ‘‘Engineers’”  ce- 
ment and  “ Plasterers’  ” cement.  The  former  is  the 
more  costly  ; it  is  usually  described  by  manufacturers 
as  “ best  heavy  tested it  weighs  from  112  pounds  to 


85 


CEMENTS,  ETC. 

120  pounds  to  the  bushel,  is  slow  setting,  and  of  great 
strength  ; the  latter  is  a light  cement,  quick  setting, 
and  of  inferior  strength  when  compared  with  the 
other.  It  must  be  understood  that  our  remarks  apply 
exclusively  to  “ Engineers’  ” cement. 

Portland  cement  is  made  from  chalk  and  alluvial 
clay ; the  factories  on  the  banks  of  the  Thames  use 
white  chalk,  those  on  the  Medwa}^  gray  chalk;  the 
latter  is  probably  preferable,  inasmuch  as  it  contains 
large  quantities  of  silicious  matter.  Mr.  Pead,  in  his 
treatise  on  “ Portland  Cement,”  says  that  “ the  present 
and  safest  proportions,  provided  both  chalk  and  clay 
are  selected  free  from  sand,  are  four  parts  of  chalk  from 
the  Medway,  (gray,)  or  three  parts  of  Thames,  (white,) 
with  one  of  clay  by  measure.”  These  materials  are 
placed  in  mills  of  simple  construction,  each  having  a 
circular  pan,  6 feet  in  diameter  and  2 feet  deep,  in 
wdiich  two  “ edge  runners,”  I feet  6 inches  in  diame- 
ter, are  kept  continually  going  ; a constant  stream  of 
’water  flows  into  the  pan,  and  as  the  edge  runners” 
revolve,  the  chalk  and  clay  are  thoroughly  ground, 
and,  being  thus  converted  into  a fluid  state,  they  Alter 
through  a band  of  flne  brass  wire  gauze  fixed  to  the 
side  of  the  pan,  and  flow  through  wooden  “ launders” 
into  tanks  or  settling  reservoirs.  One  washmill  will 
feed  four  tanks,  each  of  which  is  about  100  feet  long, 
40  feet  broad  and  4 feet  deep.  AVhen  one  of  these  has 
been  filled  in  the  manner  just  described,  the  same 
process  is  applied  to  the  others  in  succession.  About 
three  weeks  after  the  tanks  are  filled,  the  whole  of  the 
materials  will  be  precipitated,  the  clear  water  being 
drained  oif  in  the  meantime  through  a small  weir  in 
the  brick  side  of  the  tank ; the  residuum  is  a plastic 


86 


HTDRAULIO  LIMESTONE, 


mixture  of  the  consistency  of  “ putty,”  and  not  much 
unlike  it  in  color.  The  next  process  is  to  convey  this 
precipitate  from  the  tank  to  the  “ drying  floors,”  over 
which  it  is  spread  in  a layer  about  6 inches  thick  ; each 
floor  is  40  feet  by  30  feet;  it  consists  of  an  outer  skin 
of  boiler  plates,  resting  on  a series  of  brick  ovens  and 
flues.  The  object  of  this  arrangement  is  to  render 
the  plates  sufficiently  hot  to  effect  the  rapid  desicca- 
tion  of  the  water  from  the  superincumbent  layer,  a 
process  generally  accomplished  in  about  twelve  hours. 
The  materials  having  thus  been  thoroughly  dried,  are 
ready  for  conveyance  to  the  kilns.  The  “charge” 
consists  of  alternate  layers  of  coke  and  raw  materials, 
the  burning  generally  occupying  thirty-six  hours. 
When  the  contents  of  the  kiln  becomes  sufficiently 
cool,  the  “ clinkers,”  or  cement  stones — for  the  mix- 
ture has  now  assumed  that  form- — are  drawn  and  re- 
moved to  a floor  where  the  larger  pieces  are  broken, 
and  the  whole  of  the  burnt  materials  are  then  con- 
veyed to  the  hoppers  of  the  grinding  mills,  where, 
passing  under  rapidly  revolving  horizontal  burr-stones, 
they  are  ground  into  an  almost  impalpable  powder. 
The  cement  issues  from  the  mill  at  a temperature  of 
about  160°,  and  the  now  manufactured  material  is 
wheeled  away,  and  placed  in  a layer  from  2 feet  to  3 
feet  thick  over  the  floor  of  a cool  shed  ; it  is  subse- 
quently packed  in  casks  or  sacks  for  conveyance  from 
the  wmrks.  The  essential  conditions  for  the  manufac- 
ture of  sood  Portland  cement  are  : 1.  The  chalk  and 
clay  should  be  thoroughly  mixed  in  the  washrnills,  and 
the  fluid  materials  delivered  by  “ laundei's”  over  the 
entire  area  of  the  settling  tanks.  2.  The  contents  of 
the  kilns  ought  to  be  burnt  equally  throughout.  3. 


CEMENTS,  ETC. 


87 


Tlie  burnt  materials  should  be  ground  very  fine.  4. 
After  coming  fruin  the  mill  the  cement  should  be 
spread  over  the  fioor  of  a shed,  and  allowed  to  remain 
there  for  at  least  a fortnight  previously  to  being 
packed  into  casks  or  sacks. 

The  strength  of  Portland  cement  increases  as  its 
specific  gravity  increases  ; phe  tensile  tests  are  usually 
made  with  briquettes,  the  standard  size  for  the  neck 
being  IJin.  by  l|-in.  ; and  it  must  be  understood  that 
all  experiments  referred  to  have  reference  to  the 
weight  necessary  to  sever  square  inches  of  neat 
cement. 

It  appears  from  Mr.  Grant’s  valuable  paper,  read 
before  the  Institution  of  Civil  Engineers  in  December, 
1865,  that  Portland  cement  gains  from  20  to  30  per 
cent,  in  strength  by  setting  under  water;  it  is  usual, 
therefore,  to  place  the  best  briquettes  in  water,  after 
gaging,  and  allow  them  to  remain  there  until  they  are 
to  be  tested.  The  following  table  has  been  compiled 
from  a recent  series  of  experiments  ; it  shows  the 
averas^e  tensile  streno-th  of  Portland  cement  as  com- 
pared  with  the  natural  cements;  the  test  blocks  were 
of  standard  size  of  2J  square  inches,  and  placed  in 
water,  as  before  described  : 


O 

II 

1 Breaking  weight 
1 two  days  old. 

1 Breaking  weight 
1 four  days  old. 

•5  0 

> GQ 

c3 

fcJL'O 

.5  a 
§ S 

lbs. 

lbs. 

lbs. 

lbs. 

Portland  Cement, 

119 

598 

914 

1,024 

Roman  Cement, 

76 

200 

240 

280 

Medina  Cement,  

69 

280 

313 

313 

Cement  de  Zumaya,  (Spanish,) 

84 

306 

409 

88  HYDRAULIC  LIMESTONE, 

The  Builders'  Trade  Circular  vouches  for  the  ac- 
curacy of  these  figures. 

Mr.  Grant’s  tables  show  conclusively  that  the 
strength  of  gaged  Portland  cement  increases  with  age ; 
from  his  experiments,  it  appears  that  the  breaking 
weight  of  rest  blocks,  one  week  old,  one  year  old,  and 
two  years  old,  are  as  1,  1.5,  and  1.62.  The  ultimate 
maximum  tensile  strength  has  not  as  }^et  been  ascer- 
tained ; experiments  are,  however,  being  conducted 
periodically  with  a view  to  determine  this  important 
point.  Mr.  Grant  gives  the  average  tensile  strength 
of  cement  weighing  119  pounds  to  the  bushel  as  777 
pounds,  whereas  we  give  it  as  1,024:  pounds  ; the  ex- 
cess of  the  breaking  weight,  as  recorded  by  us,  may 
probably  be  accounted  for  by  improved  manufacture 
since  Mr.  Grant’s  experiments  were  made. 

Portland  cement  now  forms  an  important  item  in 
the  list  of  our  manufactures  ; but  even  now  its  valuable 
properties  are  not  as  fully  appreciated  as  they  deserve 
to  be. 

Good  Portland  cement  should  present  a fine  and 
homogeneous  powder;  it  should  set  firmly  and  quick- 
ly, when  used  in  works  exposed  to  the  surf,  filling  up 
joints  in  water  works,  etc.,  otherwise  too  rapid  setting 
is  not  desirable.  It  should  neither  contract  nor  ex- 
pand; it  ought  to  assume  a uniform,  bright,  gray-stone 
color,  free  from  brown  spots  ; it  should  possess  great 
cementing  properties,  adhere  strongly  to  the  stone, 
and  bear  a high  addition  of  sand.  Finally,  it  ought 
to  be  free  from  adulterations,  while  the  ton  should 
have  the  generally  adopted  weight  of  2U0  kilogrammes. 
It  is  to  be  recommended,  under  all  circumstances,  and 


CEMENTS.  ETC. 


89 


even  if  tlie  cement  has  been  procured  fi’om  well-known 
inanufactiirers,  to  weigh  it  on  delivery,  and  to  keep 
an  accurate  account  of  it.  It  is  very  often  the  case 
that  the  weight  is  considerably  below  200  kilo- 
grammes, due  either  to^ie  frequent  use  of  the  same 
barrel,  which  almost  inevitably  gets  smaller,  or  to 
bad  packing,  which  produces  incompactness;  or  to 
unpacking  it  in  smaller  barrels,  which  is  often  done 
by  second  or  third  hand  dealers. 

A difference  of  ten  or  twenty  kilogrammes  per  ton, 
which  often  occurs  away  from  the  centres  of  trade, 
ought  certainly  to  be  taken  into  consideration,  if  oc- 
curring in  larger  quantities. 

In  order  to  examine  cements  for  their  fineness  and 
uniformity  of  mixture,  it  is  only  necessary  to  pass 
samples  of  different  barrels  through  sieves  of  twenty 
meslies  per  centimetre. 

There  should,  properly  speaking,  remain  nothing  on 
the  sieve,  and  under  all  circumstances,  preference  must 
be  given  to  the  cement  wdiich  most  nearly  fulfills  these 
conditions  ; for  the  finer  and  more  uniformly  the  ce- 
ment is  divided,  the  more  promptly  and  simultaneously 
will  the  chemical  reactions  take  place,  the  more  perfect 
its  combining  and  cementing  properties,  and  the  less 
fear  is  to  be  entertained  about  a durability  of  the  mass 
after  it  has  once  properly  set.  The  most  common 
adulterations  are  inferior  or  spoiled  cement,  slags, 
ashes,  clay  and  sand.  They  are  most  easily  discovered 
by  constant  shaking  of  a sample  with  an  abundant 
amount  of  water,  after  which  it  is  allowed  to  settle  in 
a high,  narrow  vessel.  The  cement  to  be  examined 
is  to  be  put  in  the  glass  filled  two-thirds  full  of  water, 
after  which  it  must  be  shaken  at  once,  or  the  cement 


90 


HYDRAULIC  LIMESTONE, 


will  cake  together  and  stick  to  the  vessel.  Ashes  and 
clay  deposit  on  top,  on  account  of  their  smaller  specific 
gravity,  and  the  water  in  this  case  generally  looks 
turbid.  The  upper  portion  of  the  sediment  generally 
fails  then  to  harden  at  all,%ut  exhibits  a distinctly 
different  color  from  the  rest  of  the  mass.  A close  ex- 
amination of  it  will  then  usually  disclose  the  nature 
of  the  adulteration. 

An  addition  of  ashes  may  be  recognised  by  treating 
the  upper  layer  with  muriatic  acid,  upon  which  an 
abundant  development  of  carbonic  acid  will  take  place, 
while  a plastic  residue  indicates  an  adulteration  with 
clay. 

Sand  will  be  found  divided  throughout  the  mass, 
but  especially  in  the  lower  portions.  It  is  discovered 
in  treating  the  cement,  by  moderately  strong  boiling 
muriatic  acid,  which  dissolves  the  cement,  but  leaves 
the  sand  behind. 

Most  dangerous,  however,  because  not  recognisable 
at  all,  is  basic  slag,  or  spoiled  cement,  which  necessarily 
injures  the  binding  quality  and  strength.  An  adul- 
teration of  this  kind  is  not  very  injurious  when  the 
cement  is  not  much  exposed  to  the  action  of  water,  if 
a slag  is  employed  that  is  not  too  basic,  and  that  sets 
with  lime,  as  is  the  case  with  many  blast-furnace  slags. 
In  such  cases  it  is  acted  upon  by  the  liberated  lime, 
and  thus  it  becomes  a cement  itself,  while  superbasic 
and  very  acid  slags,  that  are  not  decomposable  by 
acids,  behave  as  inert  masses,  taking  simply  the  part 
of  sand. 

When  made  into  a paste,  with  sufficient  water  to 
produce  a mortar  which  slides  smoothly  from  the 


CEMENTS,  ETC. 


91 


trowel,  pure  cement  should  not  set  in  less  than  twenty 
or  thirty  minutes. 

Yet  the  view  that  the  most  quickly-setting  cement 
is  the  best,  is  found  to  be  quite  generally  disseminated. 
We  read,  for  instance,  in  a book  on  this  subject  of  re- 
cent date:  “ Excellent  cements,  such  as  the  Portland 
cement,  Homan  cement,  and  others,  if  immersed  in 
water,  harden  in  a few  minutes,  while  inferior  cements 
only  attain  after  a few  hours  such  a degree  of  hard- 
ness that  the}^  will  not  take  an  impression  by  the 
fingers.” 

This  view  is  not  quite  correct,  for  it  can  be  proven 
that  rapidly-hardening  cements  will,  under  otherwise 
equal  circumstances,  never  attain  such  a degree  of 
solidity  and  strength  as  slowly-setting  ones.  They 
will,  therefore,  not  bear  the  same  amount  of  sand. 

Hapidly-setting  cements  ought,  therefore,  to  be 
avoided  when  possible,  and  only  used  in  filling  up 
cracks  in  water  works,  or  for  similar  purposes;  firstljgbe- 
cause  they  fail  to  attain  the  same  degree  of  solidity  and 
power  of  resistance  as  the  slowl)^-setting  ones  ; second- 
ly, because  they  can  only  be  worked  with  difficulty  in 
small  quantities,  and  only  givdng  the  best  result  of 
which  the)^  are  capable,  when  the  mason  is  exceeding!}" 
prompt  and  skillful ; thirdly,  because  they  accomplish 
much  less  than  they  really  should  by  being  worked  in 
a careless  manner,  besides  causing  considerable  delay. 

For,  if  the  hardening  process  has  once  begun  in  the 
mortar-box,  the  most  assiduous  working  up  of  the 
solidifying  mass  will  not  (especially  if  more  water  is 
added)  entirely  remedy  the  evil. 

By  employing  slowly-binding  cements,  these  draw- 
backs are  in  a great  measure  avoided.  Portland  ce- 


92 


HTDEAULIC  LIMESTONE, 


ment,  which,  if  mixed  with  the  necessary  amount  of 
water,  say  from  thirty  to  forty  per  cent,  in  weight, 
and  if  not  setting  in  less  than  twenty  minutes,  will 
scarcely  increase  in  temperature ; quickly-hardening 
cement,  however,  will  get  hot  in  consequence  of  the 
rapid  chemical  action  which  takes  place.  Still,  there 
exist  also  limits  in  regard,  to  slew-setting.  If  it  sets 
too  slowly,  it  remains  resistless,  and  is  pressed  out  of 
the  joints,  for  which  reason  the  continuation  of  the 
work  will  be  prevented  until  the  mass  is  sufficiently 
hardened. 

If  once  set  under  water,  the  cement  should  continu- 
ally  get  harder  without  changing  its  volume,  cracking, 
or  perhaps  even  falling  to  pieces.  The  cement  should 
completely  fill  the  mould  in  which  it  has  been  pre- 
pared as  thick  paste  ; it  should  not  suffer  any  contrac- 
tion by  the  evaporation  of  water  added  in  surplus. 
On  the  other  hand,  there  should  be  no  increase  of 
volume  by  swelling. 

The  tests  to  be  made  follow  from  these  considera- 
tions : 

Small  preserve-glasses  are  filled  with  cement  and 
the  necessary  quantity  of  water;  another  portion  is 
spread  over  a glass  plate,  or  a previously  well-mois- 
tened brick,  so  as  to  form  a cake  of  about  five  centi- 
metres in  diameter,  or  a larger  surface  is  covered  with 
a layer  of  one  centimetre.  From  the  rest  some  balls 
are  formed  before  it  has  become  solid,  or  a new  por- 
tion of  the  powder  is  taken,  and  so  much  water  added 
that  balls  may  be  formed. 

A sewer  constructed  of  concrete,  consisting  of  one- 
seventh  cement  to  six-sevenths  of  sand,  and  lined  inside 
wdth  cement,  was  regarded  by  Mr.  Grant  as  the  cheap- 


CEMENTS,  ETC. 


93 


est  form  of  sewer  combining  strength  with  soundness. 
Tables  were  also  given  of  the  strength  of  589/271 
bushels  of  Portland  cement,  used  during  the  last  five 
years  on  various  works  south  of  the  river  Thames, 
showing  an  average  tensile  strain  at  the  end  of  a week 
of  806.63  pounds,  equal  to  358.5  pounds  per  square 
inch,  being  an  improvement  on  that  reported  five 
years  ago  of  89  pounds  per  square  inch.  At  the  end 
of  thirty  days,  37,200  bushels  of  the  same  cement,  as 
ascertained  by  1,180  tests,  had  an  average  strength  of 
455  pounds  per  square  inch.  Further  experience  had 
confirmed  the  earlier  conclusions  that  the  strength  of 
Portland  cement  increased  with  its  specitic  gravity,  its 
more  perfect  pulverization,  and  its  thorough  admix- 
ture with  the  minimum  quantity  of  water  in  forming 
mortar.  Heavy  cement,  weighing  123  pounds  per 
bushel,  took  about  two  years  to  attain  its  maximum 
strength  when  used  pure;  but  by  the  admixture  of 
sand  or  gravel,  cement,  mortar  or  concrete  w^as  re- 
duced in  strength,  and  set  less  rapidly  than  pure  ce- 
ment. Poman  cement,  though  from  its  quick  setting 
properly  very  valuable  for  many  purposes,  deteriorated 
after  exposure  to  air  before  use  about  twice  as  much 
as  Portland  cement,  if  measured  by  strength.  In 
making  cement  concrete,  it  would,  from  this,  seem  - 
desirable  to  spend  no  more  time  than  was  absolutely 
necessary  to  effect  a thorough  admixture  of  the  cement 
with  the  sand  and  gravel. 

Under  the  name  of  liquid  stone,  is  the  application 
of  the  alkaline  silicates  in  the  following  manner  : 


5'^ 


94 


HYDRAULIC  LIMESTONE, 


‘‘  The  first  idea  that  suggests  itself  of  the  use  of  such 
a liquid,  is  the  preparation  of  artificial  stones  for  orna~ 
mental  and  building  purposes.  Should  it  be  possible 
to  produce  this  petrifying  liquid  cheap  enough,  build- 
ing stones  in  all  their  variety  could  be  made  and 
cemented  together  with  the  same  petrifying  solution. 
The  cost  of  cast  fiint  marble  statuary,  tombstones, 
baths,  tables,  mantel-pieces  and  ornaments  of  all  kinds, 
would  be,  of  course,  much  less  than  if  laboriously  out 
from  the  stone,  and  they  come  quickly  into  universal 
use.  In  a similar  way,  as  photography  now  diffuses 
the  master-pieces  of  the  art  of  painting  among  all 
classes  of  society,  and  cultivates  their  taste,  the  art  of 
casting  fiint  marhle  would  multiply  and  difi'use  the 
master-pieces  of  sculpture,  and  adorn  our  public  build- 
ings, gardens  and  parks.  Bas  reliefs,  cameos,  cornices, 
columns,  pillars,  etc.,  might  be  produced  at  compara- 
tively cheap  prices.  Should  the  liquid  be  of  a kind  to 
permit  its  application  to  outside  or  inside  walls,  like 
plaster,  then  we  could  cover  our  brick  and  stone  houses 
with  white  or  colored  fiint-marble  fronts,  and  our 
churches,  halls,  theatres,  parlors  and  rooms  with  glass- 
like walls  and  ceilings,  colored  ad  libitum  -with  elegant 
frescoes  as  durable  as  the  still  fresh  paintings  at  Her- 
culaneum and  Pompeii ; while  the  fioors  could  be 
inlaid  with  beautifully  colored  stones  in  mosaic  style. 

“ Another  important  application  for  such  a liquid 
would  be  the  one  to  render  wood  7ion-infiammable,  rot 
and  waterproof.  By  making  wood  non-infiammable, 
we  should  greatly  diminish  the  danger  to  which  most 
of  our  old  and  new  buildings  are  now  exposed.  This 
could  easily  be  effected,  and  with  not  much  cost,  by 
impregnating  the  wood  with  a properly  prepared  sola- 


95 


CEMENTS,  ETC. 

tion  of  flint ; for,  if  once  the  pores  of  the  wood,  which 
by  their  capillary  action  cause  the  communication  of 
the  tire  to  the  whole  structure,  be  stopped  up  by  the 
incombustible  and  non-conducting  silica,  the  wood 
becomes  non-inflammable,  and  at  the  same  time  proof 
against  water  and  decay.  Not  less  important  would 
be  the  partial  silicification  of  rail-road  sleepers  and 
cross  ties,  house,  ship  and  bridge  timber  ; they  would 
be  stronger  and  last  longer.  Telegraph  poles  would, 
when  properly  treated,  become  more  durable,  and  be, 
in  addition,  better  non-conductors  of  electricity. 
What  a new  field  would  such  a petrifying  fluid  open 
to  the  manufacture  of  incombustible  paints  and  var- 
nishes ? It  might  also  be  mixed  with  paper  pulp,  or 
cheap  vegetable  or  animal  fibre,  and  serve  for  the 
manufacture  of  a variety  of  useful  articles,  such  as 
staircases,  boxes,  trunks,  soles  for  boots  and  shoes,  pat- 
terns, moulds,  handles,  parts  of  machinery,  photo- 
graphic instruments,  piano  keys ; and,  further,  it 
might  be  used  as  a coating  for  preventing  the  oxyda- 
tion  of  iron  or  other  metals.  We  must  not  overlook 
another  important  application  in  the  use  of  the  liquid 
flint — the  one  for  the  preservation  of  old  monuments 
and  stone  buildings.  It  might,  perhaps,  also  serve  as 
a medium  for  the  preservation  of  meat,  fruit,  vegeta- 
bles, eggs,  etc.  The  linings  of  barrels,  for  oils  and 
other  liquids,  the  coating  of  tanks,  tubs,  sulphurki 
acid  chambers,  etc.,  are  other  useful  applications  of 
this  liquid. 

“ Metallurgy  could  be  very  materially  benefited  by 
a process  whereby  quartz  could  cheaply  and  speedily 
be  dissolved  in  water;  for  we  could  then  take  the 
gold  quartz  of  Nova  Scotia,  New-TIampshire  or  Cana- 


96 


HYDKAULIO  LIMESTONE, 

da,  and  dissolve  the  quartz  and  obtain  all  the  gold  as 
a precipitate.  Of  course,  as  the  liquid  flint  could  be 
used  for  so  many  useful  purposes,  and  be  sold  for  a 
good  price,  the  extraction  of  the  gold  would  be  very 
cheap,  and,  so  to  speak,  cost  less  than  nothing,  as  the 
extraction  price  of  the  gold  would  be  more  than  paid 
for  by  the  amount  realized  from  the  sale  or  use  of  the 
liquid.” 

Hydraulic  Mortar  from  American  Limestone. 

These  limestones  contain  mostly  lime,  silica,  alu- 
mina, oxide  of  iron  and  magnesia,  which  form  the 
proper  materials  for  the  preparation  of  mortars  ; they 
will  withstand  the  action  of  water  and  moisture  bet- 
ter in  proportion,  as  the  quantity  of  silica,  alumina 
and  magnesia  is  larger  ; they  contain  40  per  cent, 
carbonate  of  lime,  30  per  cent,  carbonate  of  magne- 
sia, and  20  per  cent,  silica,  the  balance  is  alumina 
and  oxide  of  iron,  and  they  form  a good  mortar  and 
a good  building  material ; but  when  the  magnesia  is 
too  prevalent,  will  deteriorate  it  for  building  pur- 
poses, it  being  too  friable.  The  dolomite,  which  is 
also  called  bitterspar,  a magnesian  limestone,  is  a 
double  carbonate  of  lime  and  magnesia,  and  abun- 
dant in  the  United  States,  is  a granular  limestone, 
and  a hardness  of  3.5,  a spec.  gr.  of  3.1,  and  consist- 
ing of  70  per  cent,  lime  and  nearly  40  per  cent,  of 
magnesia  and  some  oxide  of  iron  and  manganese  ; is 
unfit  by  itself  as  a building  material,  having  a great 
tendency  to  crumble  into  small  fragments,  and  forms 
likewise  an  inferior  material  for  burning  and  con- 
verting it  into  cement,  because  it  lacks  the  silica  in- 


CEMENTS,  E,TC. 


97 


dispensable  for  this  purpose.  By  an  addition  of  an 
alkaline  silicate,  either  the  silicate  of  potash  or  soda, 
and  an  addition  of  some  alumina,  will,  after  burning, 
produce  a good  hydraulic  cement,  particularly  in  such 
localities  where  no  good  native  hydraulic  limestone  is 
found.  Not  alone  France  and  Germany  are  particu- 
larly rich  in  deposits  of  hydraulic  lime,  and  in  the 
United  States  likewise,  but  these  in  our  neighborhood 
may  be  particularly  mentioned  at  Uondout,  on  the 
western  shore  of  the  Hudson  Kiver,  100  miles  distant 
from  New-York.  The  quarrying  in  those  subterra- 
nean rocks  for  hydraulic  cement  and  also  common 
limestone  is  carried  on  in  that  region,  along  a large 
extent  of  the  valley  of  the  Kosedale  Hiver  ; through 
this  valley  the  Hudson  and  Delaware  Canal  is  con- 
structed, which  brings  the  coal  from  the  Lackawanna 
valley  at  Carbondale  directly  to  the  Hudson  Hiver. 
This  coal  being  a very  pure  anthracite,  is  admirably 
adapted  for  use  in  the  limestone  and  cement  furnaces 
situated  at  the  junction  of  this  canal  with  the  Hudson 
Hiver. 

In  burning  hydraulic  limestone,  not  only  the  car- 
bonic acid  and  water  of  hydration  are  drawn  off,  as  is 
the  case  with  common  limestone,  but  after  the  lime 
and  magnesia  have  parted  with  their  carbonic  acid,  at 
the  high  temperature  of  the  furnace,  they  act  on  the 
silica  and  alumina,  as  it  were,  like  twm  powerful  bases, 
and  a silicate  of  lime  and  magnesia,  as  also  silicate  of 
alumina  and  aluminate  of  lime,  are  formed.  The  ex- 
act chemical  reaction  during  the  burning  process  is, 
however,  as  yet  not  well  understood,  and  undoubtedly 
varies  in  different  limestones,  according  to  their 
chemical  constitution,  which  latter  appears  also  to 


98 


HYDRAULIO  LIMESTONE, 


vary  considerably,  but  without  affecting  materially 
their  useful  properties. 

In  regard  to  the  theoretical  causes  of  the  liardening 
process,  which  takes  place  under  water,  it  may  be  re- 
marked that  this  curious  and  interesting  phenomenon, 
being  of  an  entirely  chemical  nature,  has  largely  drawn 
towards  itself  the  attention  of  eminent  chemists,  who 
have  attempted  to  explain  it  in  accordance  with  well 
known  chemical  laws.  All  hydraulic  limestones  may, 
by  the  ordinary  method  of  analysis,  be  decomposed 
into  two  component  parts  ; the  one  consisting  of  the 
carbonates  of  the  earth,  such  as  lime,  magnesia,  etc., 
which,  like  ordinary  limestones,  yield  a fat  lime  ; the 
other,  a silicate,  or  rather  a mixture  of  the  silicates  of 
alumina,  magnesia,  lime,  and  sometimes  potassa,  as  we 
find  in  the  felspar,  which  is  a silicate  of  alumina  and 
potash,  and  a greater  or  less  excess  of  free  silica  ; the 
latter  constituent  is,  therefore,  simply  a kind  of  clay. 
The  reaction  during  the  burning  process  has  been 
already  alluded  to.  Now,  when  such  freshl}^  burnt 
cement  is  mixed  with  water,  the  excess  of  caustic  lime 
as  well  as  the  compound  into  which  the  silicious  clay 
has  been  converted  during  the  burning,  react  upon 
one  another  in  such  a manner,  tliat  a solid  stone-like 
silicate  is  produced  in  the  humid  way,  the  water  has 
a double  action ; dry  substances,  such  as  lime  and  sili- 
cate of  alumina,  do  not  act  one  upon  another,  unless 
the  solvent  power  of  water  is  brought  into  play  so  as 
to  bring  them  into  close  contact;  the  water  transfers 
continually  the  lime  it  dissolves  to  the  silica.  The 
absolute  necessity  of  keeping  such  mortar  under  water, 
in  order  to  have  it  harden,  is  thus  explained.  Another 
action  of  the  water  is  this  : it  enters  into  a state  of 


99 


CEMENTS,  ETC. 

hydration  in  the  silicate  of  lime  as  soon  as  formed.  It 
must  also  be  observed,  that  the  molecular  condition  of 
the  silica  is  of  the  utmost  importance  in  this  process. 
Fine  sand  will  not  combine  with  lime,  when  the  latter 
is  dissolved  in  water  that  is  in  a form  known  under 
the  name  of  limewater  ; but  silica,  precipitated  from  a 
soluble  glass  solution  by  means  of  an  acid,  which  pro- 
duces the  gelatinous  form  of  silica,  will  at  once  com- 
bine with  the  lime  in  limewater  and  form  a silicate  of 
lime.  The  silica  in  the  hydraulic  mortar  is  also  in  a 
state,  not  like  tine  sand,  but  chemically  combined  and 
dissolved  iji  the  mass,  and  therefore  ready  to  combine 
with  the  lime  in  limewater.  Next  in  importance  to 
silica  is  the  magnesia,  which  renders  the  lime  hydrau- 
lic, which,  according  to  Fuchs,  has  been  proved  that 
lime  and  magnesia  well  mixed  will  harden  under 
water  to  a certain  extent  without  the  addition  of  silica; 
for  we  have  in  Germany  a hydraulic  lime  containing 
only  4 per  cent.  When  silica  is  found  to  the  extent 
of  52  per  cent.,  the  point  of  saturation  is  reached,  and 
such  limestone  is  no  more  hydraulic.  Alumina  and 
iron  may  be  entirely  absent,  although  the  former  is 
always  present  in'the  best  kinds  of  hydraulic  mortars, 
of  which  that  of  Eondout,  usually  called  Kosedale 
cement,  and  wdth  the  employment  of  which  the  Croton 
Water  Works  of  New- York  City  w’ere  built,  is  the 
best  on  this  continent. 

It  is  conhdently  to  be  hoped,  that  by  the  proper 
application  of  alkaline,  silicates  will  contribute  much 
to  the  manufacture  of  an  artificial  hydraulic  cement. 


100 


HYDRAULIC  LIMESTONE, 


German  Hydraulic  Cement. 

This  material,  artificially  prepared,  is  in  great  use, 
and  is  of  very  peculiar  composition  ; unquestionably 
it  is  intended  to  form  a silicate-aluminate  of  lime,  or, 
in  other  words,  an  argillaceous  silicate,  but  the  ad- 
mixture, such  as  charcoal  and  iron  filings,  cannot  be 
explained,  but  the  base  being  obtained  by  the  pro- 
duction of  an  alkaline  silicate,  bespeaks  for  it  a usefnl 
vehicle  as  a cement. 

It  is  prepared  with  25  parts  common  clay,  60  parts 
lime,  10  parts  magnesian  limestone,  10  parts  iron 
filings,  and  10  parts  of  black  oxide  of  manganese ; 
these  materials,  in  very  fine  powders,  are  made  plastic 
by  the  liquid  silicate  of  soda,  at  once  applied  as  a 
cement  or  mortar,  but  it  will  not  set  at  once,  six  hours 
being  required  for  the  mass  to  harden. 

Hardness  of  Ancient  Mortars. 

Mr.  Spillar  communicated  a paper  on  this  subject 
to  the  British  Association  in  1868,  of  which  the  fol- 
lowing are  the  conclusions,  from  the  chemical  exami- 
nation of  the  ancient  mortars  from  Burgh,  Pevesney, 
and  other  Boinan  castles  : that  the  lime  and  carbonic 
acid  are  invariably  united  in  monatomic  proportions, 
as  in  the  original  limestone  rock ; and  that  there  is 
no  evidence  of  the  hydrate  of  lime  having  at  any 
time  exerted  a power  of  corroding  the  surfaces  of 
sand,  fiint,  pebbles,  or  even  of  burned  clay,  with 
which  it  must  have  been  in  contact  for  long  periods. 
Further,  that  the  water  originally  combined  with  the 


CEMENTS,  ETC. 


101 


lime  has  been  entirely  eliminated  during  this  process 
of  recarbonation  ; and  this  stage  passed,  the  amor- 
phous carbonate  of  lime  seems  to  have  been  gradually 
transformed  by  the  joint  agency  of  water  and  carbonic 
acid  into  more  or  less  perfectly  crystalized  deposits  or 
concretions,  by  virtue  of  whicli  its  binding  properties 
must  have  been  very  considerably  augmented.  Messrs. 
Abel  and  Bloxarn  assign,  as  one  of  the  causes  of  the 
hardening  of  mortars,  the  formation  and  subsequent 
crystal ization  of  the  carbonate  of  lime. 

Stinde  proposes  the  silicate  as  a very  useful  cement, 
by  mixing  equal  parts  of  oxide  of  manganese  and 
oxide  of  zinc,  and  making  them  into  a thinish  paste 
with  the  silicate  of  soda,  which  paste,  quickly  applied, 
sets  very  rapidly  ; and  by  mixing  the  hydraulic  lime 
to  this  composition,  it  is  a cement  which  will  resist 
permanently  also  the  action  of  water  and  heat. 

“ Cement  and  Mortar  of  the  Ancients. 

‘‘We  all  know  how  enthusiastic  some  are  in  their 
praises  of  those  ancient  structures  which  have  resisted 
for  ages  the  ravages  of  time.  They  imagine  that  they 
are  at  liberty  to  draw  conclusions  which  are  not  the 
most  favorable  to  the  architecture  of  the  present  time. 
Although  they  may  be  in  a measure  correct,  it  cannot 
be  denied  that  such  critics  are  too  partial  in  their  ad- 
miration for  things  ancient  as  opposed  to  things 
modern.  We  frequently  hear  the  remark  that  some 
of  the  Koman  mortars  have  endured  for  eighteen  cen- 
turies the  vicissitudes  of  time,  while  many  buildings 
of  now-a-days  present,  in  a very  brief  period,  the  sign 
of  quick  decay;  but  they  forget  that  these  ancient 


102 


HYDRAULIC  LIMESTONE, 


buildings  constitute  an  exceedingly  small  fraction  of 
the  enormous  number  of  those  erected  during  many 
centuries  in  Egypt,  Greece,  Home  and  her  provinces. 
They  do  not  consider  that  thousands  of  temples,  pala- 
ces, and  private  dwellings  have  been  entirely  de- 
stroyed. And  what  answer  can  they  assign  to  the 
fact  that  the  very  complaints  they  indulge  in  were 
even  more  frequent  then  than  now?  Pliny  asserts 
that  the  reason  of  the  falling  in  of  many  buildings  in 
Pome  was  to  be  attributed  to  the  fact  of  the  bad 
quality  of  the  mortar. 

“ Still  more  important  than  this  argument  is  that 
of  Vitruvius,  the  architect  of  Augustus*.  lie  has  left 
a work  on  Roman  architecture  in  wdiich  we  find 
nothing  that  entitles  us  to  place  the  architects  of  an- 
tiquity above  those  of  the  present  time.  Again,  it  has 
not  been  taken  into  account  that  a great  part  of  the 
extraordinary  strength  of  antique  architecture  is  more 
the  effect  of  time  than  the  mechanical  skill  of  the 
builder,  or  the  virtues  of  his  cements,  as  we  propose 
to  show  hereafter.  Pliny  and  Vitruvius  both  explain, 
to  the  best  of  their  knowledge,  what  kind  of  materials 
the  builders  selected  for  their  cements,  and  how  they 
were  prepared.  The  process  was  identical  with  the 
modern  modus  operandi.  It  is  true  that  the  old  Ro- 
mans were  particularly  careful  in  the  selection  of  ma- 
terials for  their  mortar,  as  well  as  in  its  preparation. 
They  were  aware  that  they  must  calcine  the  limestone, 
and  mix  it  with  sand,  in  order  to  apply  it ; but  did 
not  possess  any  correct  idea  of  the  change  which  lime- 
stone undergoes  in  the  process  of  calcination,  nor  of 
that  which  is  the  cause  of  the  cohesive  quality  of 
mortar. 


CEMENTS,  ETC. 


103 


“ Many  centuries  elapsed  before  these  bicts  ^Yere 
understood  and  explained.  Black,  in  1757,  started 
the  explanatory  theory  by  the  discovery  of  carbonic 
acid.  A few  years  previous  to  this,  Marggraf,  the 
discoverer  of  sugar  in  beets,  found  the  elements  of 
gypsum,  which  was  already  employed  by  the  Romans; 
and,  in  170S,  Lavoisier  demonstrated  the  causes  of  the 
liardening  of  burnt  gypsum  when  it  is  mixed  with 
water. 

“ The  ancients,  therefore,  put  their  practical  know- 
ledge to  the  best  possible  account.  As  they  were  de- 
ficient in  chemical  knowledge,  they  were  guided  only 
by  what  observation  taught  them.  Their  chief  care 
was  centred  in  the  exterior.  In  the  selection  of  lime- 
stone. the  color  decided.  Tlie  white  ones  were  con- 
sidered best,  and  the  colored  ones  were  seldom  used. 
Those  taken  from  the  interior  of  the  earth  were  pre- 
ferred to  the  stones  wdiich  were  met  with  upon  the 
shores  of  rivers.  A law  provided  that  the  lime  must 
liave  been  slaked  three  years  before,  it  could  be  used. 
The  same  also  prescribed  the  quantity  of  sand  which 
must  be  mixed  with  the  lime,  mentioning  also  that 
crushed  cherts  imparted  a greater  strength  to  the 
mortar.  Its  preparation  was,  as  it  were,  a state  affair, 
the  censors  watching  carefully  over  it.  In  spite  of  all 
this,  it  often  happened,  as  Pliny  states,  that  they  did 
not  attain  the  object  in  view. 

“ But  in  the  advance  of  chemical  science,  the  fact 
lias  been  established  that  a mortar  can  be  prepared 
that,  in  the  course  of  one  or  two  ^’ears,  will  be  as  strong 
and  durable  as  Roman  mortar  after  the  lapse  of  two 
thousand  years.  The  builders  of  the  ancients  were 
not  farther  advanced  than  those  of  the  middle  ages. 


104  HYDRAULIC  LIMESTONE, 

The  walls  of  the  Bastile,  for  instance,  were  so  strong 
that  they  had  to  be  blasted  away.  This  had  likewise 
to  be  done  in  the  removal  of  the  remnants  of  a bridge 
at  Agen,  built  about  the  year  1200 ; and  the  mortar 
of  a bridge  erected  at  Cahours  in  1400  was  even  found 
to  be  considerably  stronger  than  that  of  the  antique 
theatre  of  the  same  city. 

“ The  Homans  were  also  acquainted  with  hydraulic 
cement.  The  merit  of  this  knowledge  is,  however, 
considerably  lessened,  when  we  consider  that  the  same 
is  found  in  the  volcanic  districts  of  Southern  Italy. 
A mere  accidental  observation,  the  same  being,  per- 
haps, mixed  with  sand  instead  of  lime,  may  have  led 
to  its  application.  Says  Vitruvius:  ‘There  exists  a 
kind  of  dust  which  produces  strange  things  ; it  is 
found  near  Baja  and  the  Vesuvius.  When  mixed  with 
lime,  it  forms  a mortar  which  not  only  imparts  great 
strength  to  buildings,  but  also  to  water-works.’ 

“ The  natural  cement  in  question  is  a volcanic 
pumice-stone,  like  breccia,  which  is  still  found  in  the 
environs  of  Naples.  At  a less  remote  period  of  time, 
when  the  Homans  invaded  the  valleys  of  the  Lower 
Hhine,  they  easily  recognised  the  volcanic  nature  of 
the  Brohl  Valley.  Here,  as  well  as  amid  the  sur- 
roundings of  the  beautiful  Laacher  Lake,  which  lies 
like  a jewel  set  in  the  midst  of  the  long-extinct 
Hhenish  volcanoes,  they  discovered  another  natural 
cement — the  trass — in  such  considerable  quantities, 
that  the  quarries  which  were  opened  at  that  time  are 
still  in  existence.  The  use  of  hydraulic  cement  in 
ancient  times  could,  therefore,  have  been  only  a 
limited  one,  as  it  was  found  only  at  the  two  places 
mentioned.  Its  artificial  preparation  was  not  under- 


105 


CEMENTS,  ETC. 

stood.  The  solution  of  this  problem  was  reserved  for 
the  investigating  minds  of  the  present  progressive 
century.” 


“ Hydraulic  Cement. 

This  material  is  justly  esteemed  far  superior  to 
metal  of  any  description  for  the  lining  of  cisterns,  the 
water-prooting  of  cellar-bottoms,  and  similar  purposes. 
•A  few  directions  for  its  preparation  and  use  may  not 
be  out  of  place.  To  make  water-proof  work,  it  must 
be  borne  in  mind  that  common  lime  must  not  be  used 
at  all;  for  on  common  lime  water  or  moisture  has  an 
effect  just  the  opposite  to  that  which  it  has  on  the 
water  lime^  rendering  it  soft  and  quite  friable  when 
dried  ; whilst  on  the  water  lime  the  well-known  effect 
is  to  make  it  perfectly  hard.  JSTo  mixture  of  these  two 
varieties  of  lime  can,  therefore,  be  made  under  water. 
Blit,  although  they  do  not  act  well  together  even  under 
ground,  they  serve  well  in  dry  places,  such  as  build- 
ings whose  walls  are  of  extra  thickness  ; and  if  proper 
care  be  taken,  they  will  conjointly  form  a very  com- 
pact and  powerful  cement.  The  fact  that  water  lime 
shrinks  when  wet,  while  common  lime,  in  the  same 
state,  swells,  at  once  points  out  the  manner  of  treat- 
ment to  be  pursued  in  uniting  the  two  thoroughly. 
Thus,  it  is  necessary  to  ascertain  the  per  centage  of 
shrinking  of  the  one  and  increase  in  the  other,  as 
nearly  as  possible,  before  the  proportion  of  one  to  the 
other  can  be  determined,  with  a view^  to  their  intimate 
combination.  Such  experiments  are  the  more  neces- 
sary when  we  consider  the  great  difference  wdnch  ex- 
ists in  the  quality  of  both  kinds  of  lime  in  various  lo- 


106 


HYDEAULIO  LIMESTONE, 


calities.  The  simplest  and'most  effectual  mode  of 
testing  water  lime  is  to  put  several  portions  of  different 
makes  into  small  bags  of  flannel,  and  throw  them  into 
a basin  of  water.  After  three  minutes’  immersion, 
take  them  all  out  at  once,  and  squeeze  each  in  the 
hand.  Then  take  off  each  bag,  and  that  which  is  best 
\%  firmest^  and  when  thrown  naked  into  the  W’ater 
again,  loses  least  of  its  outer  coat.  If  none  of  them 
will  bear’uncovering  at  three  minutes,  try  four,  five 
minutes,  but  this  latter  should  be  the  longest  test. 
The  test  for  common  lime  is,  on  the  contrary,  the 
bursting  open  and  evolving  of  caloric  in  a greater  or 
less  degree  ; and  the  consequent  action  of  the  water 
will  show,  by  its  bubbles,  the  power  of  the  lime. 

“ It  is  the  per  centage  of  clay  contained  in  any 
specimen  of  lime  that  determines  the  solidifying  pro- 
perty of  the  cement  made  from  it.  The  best  hy- 
draulic lime  contains  silex,  lime  and  magnesia,  or 
alumina.  Its  solidification  is  attributable  to  the  for- 
mation of  silicate  of  alumina  and  lime,  or  of  magnesia 
and  lime,  which  combines  with  water,  and  produces  a 
hydrate  excessively  hard  and  insoluble  in  water.  The 
hardening  of  hydraulic  lime  may,  then,  be  compared 
to  that  of  calcined  plaster,  which  also  combines  with 
water  to  form  a solid  hydrate  ; which  calcined  plaster, 
from  the  large  quantities  of  it  manufactured  near  that 
city,  is  commonly  known  as  Plaster  of  Paris,  A 
limestone  containing  thirty  per  cent,  ot  clay  makes  a 
quick-setting  cement ; and  we  have  in  the  United 
States  the  Uosedale  and  the  Belleville  cements,  having 
forty  and  lifty  per  cent.  They  become  exceedingly 
hard  when  plunged  in  water  for  from  two  to  three 


CEMENTS,  ETC. 


107 


minutes.  Botli  these  cements,  especially  the  former, 
have  been  used  extensively  by  our  engineers. 

Inferiority  in  the  quality  of  hydraulic  lime  may 
be  produced  by  the  want  of  proper  care  during  its 
manufacture,  the  stone  being  calcined  at  too  high  a 
temperature  ; the  double  silicate  in  such  case  becom“ 
ing  a sort  of  frii^  which  does  not  hydrate  in  contact 
with  water. 

“ As  hj’draulic  lime  is  expensive  according  to  the 
distance  of  its  transportation,  we  will  here  give  the 
method  of  making  an  artificial  hydraulic  lime,  accord- 
ing to  the  highly  successful  experiments  of  M.  Yicat,  a 
celebrated  French  engineer,  and  the  author  of  a much 
esteemed  work  on  hydraulic  cement,  who  first  pointed 
out  the  method  to  be  adopted  in  its  formation.  It  is 
prepared  by  stirring  into  water  a mixture  of  one  part 
of  clay  and  four  parts  of  cbalk  ; these  materials  should 
be  mixed  by  a vertical  wheel  turning  in  a circular 
trough,  and  made  to  flow  out  into  a large  receiver.  A 
deposit  soon  takes  place,  which  is  formed  into  small 
bricks,  which,  after  being  dried  in  the  air,  are  mode- 
rately calcined.  Hydraulic  lime  thus  prepared  en- 
larges about  two-thirds  in  volume  when  placed  in 
water.  Like  the  natural  hydraulic  lime,  it  can  be 
completely  dissolved  by  acids.  This  invention  of  arti- 
ficial hydraulic  lime  has  rendered  Yicat  deservedly 
famous,  as  it  has  been  in  use  for  many  years  in  the 
public  works  throughout  France,  and*was  even  em- 
ployed in  the  hydraulic  masonry  of  the  St.  Martin 
canal.  That  it  can  be  made  in  this  country  there  is 
no  doubt,  as  tbe  argillaceous  or  potter’s  clay  required 
is  to  be  found  almost  everywhere. 

The  new  cement  which  M.  Sorel  proposed  to  the 


108 


HYDRAULIC  LIMESTONE, 


French  Academy  consists  in  the  application  of  a basic 
hydrated  oxychloride  of  magnesium,  may  unquestion- 
ably be  improved  by  means  of  a silicated  hydraulic 
lime  and  the  bittern  of  the  salines,  which  is  a chloride 
of  magnesium  in  a concentrated  condition. 

Lime,  sand  and  clay,  when  mixed  with  water,  form 
the  so-called  composition  of  a hydraulic  cement ; they 
are  fit  to  unite  solid  surfaces  by  hardening  after  a few 
days’  application,  under  water,  by  forming  a combi- 
nation with  the  constituents  of  either  surface.  Walls 
and  piers  have  been  built  for  over  one  hundred  years, 
and  after  being  exposed  under  water  have  become 
harder  and  harder.  This  cement  is  also  called  Ko- 
rn an  cement,  because  the  natural  materials  are  found 
in  abundance  in  the  Koman  district  where  the  tufas, 
puzzuolanas  and  trass,  all  products  of  volcanic  districts, 
like  the  Pontine  Marshes  of  Pome,  and  near  Naples, 
are  abundant,  and  consist  of  those  elementary  sub- 
stances. In  the  voltaic  formations  of  the  triassic  pe- 
riod the  marls  or  green  sand,  the  curious  nodular  and 
lenticular  concretions,  the  Septarias  and  Indus  Hel- 
montii,  of  turtle  shape,  all  found  in  argillaceous  strata 
of  the  sedimentary  rocks  which  are  alternating  with 
limestone  beds,  and  all  found  in  abundance  on  the 
English  and  French  coasts  and  the  United  States,  all 
of  them  form  a silicious  clay  intermixed  with’  lime, 
and  are,  therefore,  the  proper  material  for  a hydraulic 
lime  or  cement, 


109 


CEMENTS,  ETC. 


Injection  of  Silicates. 

While  engaged  in  impregnating  the  soluble  silicates 
into  the  porous  stones,  and  carrying  this  operation  into 
all  organic  and  inorganic  matter,  the  convincing  proof 
was  manifested  that  the  hardening  of  these  bodies  are 
only  owing  to  the  decomposition  of  the  silicates,  effected 
by  the  slow  action  of  the  atmospheric  carbonic  acid 
and  the  gradual  condensation  of  silica.  This  pheno- 
mena led  to  the  observations  that  the  natural  silicates 
and  all! ruinates,  as  well  as  other  mineral  species,  were 
similarly  formed  in  the  moist  way. 

This  remarkable  reaction  of  hardening  porous  bodies 
by  silica  proves,  by  geological  observations,  highly 
probable  that  not  alone  all  the  enveloped  and  crystal- 
ized  minerals  found  in  limestone  formations,  but  also 
an  endless  variety  of  silicated  and  aluminated  sub- 
stances found  in  nature,  owe  their  existence  to  analo- 
gous causes ; that  the  flints,  agates  and  petrifled  wood 
cannot  have  any  other  origin,  but  that  they  are  formed 
by  the  slow  decomposition  of  a silicated  alkali  from  the 
carbonic  acid,  either  atmospheric  or  generated  during 
the  process. 

This  fact  is  of  the  highest  interest  in  the  chemico- 
physical  investigations,  and  is  the  key  to  the  investi- 
gations of  the  formation  of  the  natural  silicates,  even 
under  many  various  circumstances,  of  the  condensa- 
tion of  silica  by  other  bodies  than  the  carbonic  acid ; 
many  experiments  undertaken  have  proved  the  gra- 
dual decomposition  as  already  stated,  and  in  a great 
variety,  of  the  formation  of  such  as  opal,  quartz,  and 
others  depending,  likewise,  of  the  state  of  concentra- 

6 


110  HtBKArLiC  LiMESTOKJIj 

tion  of  the  original  decomposed  materials.  The  irides- 
cence of  the  opal,  which  disappears  if  exposed  long  to 
dry  atmosphere,  but  revives  if  moistened  in  water  or 
sweet  oil,  gives  a beautiful  example.  Many  important 
facts  have  come  to  light  by  the  investigations  made  on 
hydraulic  limes  and  artificial  stones,  which  prove  that 
a considerable  quantity  of  potash  is  contained  in  the 
natural  hydraulic  and  other  cements  ; the  origin  of 
which  is  attributed  to  the  decomposition  of  the  alka- 
line silicates  by  the  lime,  and  this  may  be  proved  by 
the  formation  of  saltpetre  or  nitrate  of  potash  in  the 
efflorescences  of  walls  and  earths  in  caves,  called  an 
eremacausis  of  substances  which  contain  nitrogen,  and 
form,  therefore,  ammonia,  and  in  contact  with  porous 
substances  undergo  an  oxydation  and  conversion  into 
nitric  acid,  and  at  once  is  combined  with  the  alkalies 
contained  in  the  native  lime  occurring  in  the  older 
formations,  and  was  separated,  under  certain  circum- 
stances, from  the  alkaline  silicates  found  in  those  lime- 
stones— nitrate  of  potash  the  result.  In  general  terms, 
nitre,  or  nitrate  of  potash,  which  is  found  in  crusts  on 
the  surface  of  the  earth,  on  walls  and  rocks,  and  in 
caves,  is  found  in  those  localities  in  certain  soils  of 
Spain,  Egypt,  Persia  and  East  Indies,  especially  in  hot 
weather  succeeding  rains  ; it  is  also  manufactured  from 
soils  where  other  nitrates  (nitrate  of  lime  or  nitrate  of 
soda)  form  in  a similar  manner,  and  beds  called  nitra- 
ries  are  arranged  for  this  purpose  in  many  countries. 
Pefuse  animal  matter  also,  putrified  in  calcareous  soils, 
gives  rise  to  nitrate  of  lime,  as  we  find  it  so  frequently 
n cow  and  horse  stables,  and  is  then  converted  into 
nitrate  of  potash  ; old  plaster  walls,  wfflen  lixiviated, 
afford  about  5 per  cent,  of  nitre.  It  is  known  that 


CEMENTS,  ETC. 


Ill 


nitre  requires  for  its  formation  dry  air  and  long  periods 
without  rain ; the  potash  comes  mainly  from  the 
debris  of  felspathic  and  lime  rocks  in  the  soil,  or  in 
*the  cements,  if  they  have  been  used  for  building  walls, 
and  the  oxydation  of  the  nitrogen  of  the  air  is  pro- 
moted by  organic  matters,  hence  the  nitre  is  generally 
associated  with  azotized  decomposed  organic  substan- 
ces. A nitre  crust  from  the  vicinity  of  Constantine, 
Algeria,  afforded  Eoussingault  85  per  cent,  nitrate  of 
potash,  with  some  nitrate  of  lime,  soda  and  magnesia. 
In  tlie  Mammoth  Cave  of  Kentucky,  where  the  nitre 
is  found  scattered  through  the  loose  earth  in  great 
abundance,  and  was  utilized  during  the  war  of  1812, 
also  in  the  Mississippi  Valley,  in  Missouri,  many  caves 
liave  yielded  the  nitre  winch  was  of  great  use  to  the 
secessionists  of  the  late  war,  when  Tennessee,  along 
the  limestone  slopes  and  in  the  gorges  of  the  Cumber- 
land table  land,  produced  a large  amount  of  salt- 
petre. 

The  nitrate  of  soda,  formed  in  a similar  manner 
like  that  of  nitrate  of  potash,  but  more  particularly 
found  in  the  dry  pampas  of  Chili,  where  it  is  found 
at  a height  of  3,300  feet  above  the  sea,  contains  beds 
of  several  feet  in  thickness,  along  with  gypsum, 
common  salt,  glauber  salt,  and  the  remains  of  recent 
shells,  indicating  the  former  presence  of  the  sea. 

Kuhlmann  has  proved  bj"  his  investigations  that 
the  larger  number  of  limestones  from  various  geologi- 
cal periods  contain  both  potash  and  soda,  deriving 
their  existence  from  various  plants  growing  in  a cal- 
careous soil,  and  has  also  shown  the  development  of 
the  efflorescence  of  the  carbonates  of  potash,  chlorides 
of  potassium  and  sodium,  which  make  their  appear- 


112  HYDRAULIC  LIMESTONE, 

ance  on  the  surface  of  walls  from  their  construction, 
to  which  he  was  led  by  the  fact  that  the  alkaline  salts 
in  general  are  obtained  in  larger  quantities  from  hy- 
draulic limes  than  from  the  lixiviation  of  air  limes  ; 
that  the  hydraulic  limes  contain  mostly  more  alkali ; 
that  it  exerts  much  influence  upon  the  quality  of 
lime;  and  it  has  been  ascertained  by  Yicat  that  the 
occurrence  of  the  potash  and  soda  is  neither  accidental 
nor  less  influential  upon  the  proportion  of  the  hy- 
draulic limes.  It  is  presumed  that  the  silicated  lime- 
stone, and  any  fat  lime  mixed  with  clay  by  the  influ- 
ence of  potash  or  soda,  are,  during  the  burning,  con- 
verted into  double  compounds,  analogous  to  the  nat- 
ural silicates,  which  are  known  under  the  name  of 
zeolites,  such  as  mesotype,  stilbite,  apophylite,  etc., 
which  all  form  hydrates,  and  lose  their  water  of  crys- 
talization  by  burning,  and  absorb  it  again  on  moist- 
ening ; one  of  the  species  of  that  class  of  mineral, 
such  as  the  laumonite,  which,  when  exposed  for  some 
time  to  the  atmosphere,  efiloresces  and  crumbles  to 
pieces  to  the  chagrin  of  the  mineral  collectors,  but  it 
is  sufficient  to  confirm  the  remark  just  made  regard- 
ing their  constitution  and  similarity  of  the  artificial 
silicates  of  lime  and  alumina.  It  is  apparent  that,  in 
the  hardening  of  hydraulic  lime,  a process  takes  place 
analogous  to  that  of  gypsum  when  hardening,  and 
forming  a hydrate.  It  may,  however,  be  possible  that 
the  hydraulic  limes  be  still  formed  without  the  pres- 
ence of  potash  or  soda,  and  that  the  silicium  or  alu- 
minum in  contact  with  lime  fills  the  same  office  in 
possessing  the  property  of  binding  the  water,  and  to 
convert  them  in  certain  conditions  to  a hydrate. 
Hespecting  the  cement  which  is  formed  by  the  moist 


CEMENTS,  ETC. 


113 


way,  it  is  a fact  that  when  chalk  is  brought  in  contact 
with  solutions  of  alkaline  silicates,  an  exchange  of  the 
acids  of  both  salts  takes  place,  one  part  of  the  chalk  is 
converted  into  silicate  of  lime  and  the  corresponding 
quantity  of  potash  in  carbonate  of  potash  ; this  ex- 
plains the  true  artificial  stone,  which  has  become,  on 
exposure  to  the  atmosphere,  so  hard,  that,  if  the  mix- 
ture contains  a sufiScient  quantity  of  a silicate,  pos- 
sesses the  property  to  adhere  firmly  to  such  bodies 
where  it  has  been  applied,  the  materials  so  formed 
with  the  silicate  of  potash  or  soda  are  analogous  to 
cements  without  burning,  and  may  be  used  for  restor- 
ing monuments,  etc.  In  the  silification  of  artificial 
stones,  the  affinity  of  lime  to  the  silica  contained  in 
the  soluble  glass  is  manifest,  and  shows  the  effect  of 
the  alkaline  silicates  on  limestones  ; and  how  the  in- 
fluence of  the  atmosphere  in  the  hardening  of  silicates 
or  artificial  limes  is  brought  to  bear  through  the  at- 
mospheric carbonic  acid  by  the  separation  of  one 
part  of  silica  in  the  silicates,  and  how  the  other  parts 
of  the  silicate,  when  in  close  contact  with  a sufficient 
quantity  of  carbonate  of  lime,  a lime  silicate  is  formed. 

This  acquired  knowledge  has  produced  numerous 
applications  in  industry ; it  has  proved  that,  by  arti- 
ficial impregnation  of  mineral  substances  into  the  in- 
terior of  porous  substances,  organic  as  well  as  inor- 
ganic matters  are  preserved,  or  silicified.  The  silici- 
fication  of  fine  sandstone  is  easily  effected  by  the 
mixture  of  1 part  of  liquid  silica,  and  2 parts  of  fine 
sand,  with  the  addition  of  a small  quantity  of  chalk 
and  white  clay,  all  of  which  are  wrought  into  a paste, 
and  then  formed  into  desired  objects  and  exposed  to 
the  atmosphere  for  some  time,  and  the  finishing  pro- 


114  HYDRAULIC  LIMESTONE,  CEMENTS,  ETC. 

cess  continued  bj  means  of  hydraulic  pressure  and 
heating  in  hot  chambers,  the  particulars  of  which  have 
been  indicated  in  a former  chapter.  It  has  been  as- 
certained that  always,  if  any  salt  insoluble  in  water  is 
brought  in  contact  with  the  solution  of  a salt  which 
forms  with  the  acid  of  the  base  of  the  insoluble  salt  a 
less  soluble  substance,  an  exchange  takes  place,  which, 
although  but  partial  sometimes,  produces  the  forma- 
tion of  double  salts.  This  discovery  led  to  a direct 
application  that  white  lead,  chromate  of  lead,  chromate 
of  lime,  and  the  majority  of  the  carbonated  metallic 
salts,  are  suitable  for  silicification. 


THE  SILICATE  PAINTING  ON  STONE, 

Stereo-Chromic. 

The  1136  of  the  brush  in  the  application  of  colors 
has  so  far  been  but  partially  accomplished.  The  sub- 
stitution of  the  potash  or  soda  silicate  for  the  fixed  and 
volatile  oils  with  mineral  colors,  has  at  first  been  at- 
tempted bj^  trituration  of  white  lead  with  the  liquid 
silicate.  It  has  been  found  that  a transformation  of  the 
white  lead  takes  place  the  moment  they  come  in  con- 
tact together,  which  is  so  rapid  that  no  time  is  allowed 
to  transfer  the  paint  into  the  brush.  In  order  to  make 
this  paint  more  suitable,  and  to  prevent  a kind  of  de- 
composition, it  was  found  advisable  to  add  a large 
portion  of  the  sulphate  of  baryta,  artificially  prepared, 
as  this  paint  operates  but  slowly  on  the  silicate  solu- 
tion. 

It  appears  that  this  baryta  may  be  used  with  more 
advantage  by  itself,  as  it  unites  perfectly  with  the 
silica,  and  a^^pears  to  form  a chemical  compound,  but 
a disadvant5:ge  presents  itself  in  forming  but  a half 
transparent  color,  which  does  not  cover  well,  and  the 
addition  of  o;ide  of  zinc  is  therefore  recommended, 
which  agrees  veil  with  the  paint  in  connection  with 
baryta  and  silica;  this  application  has  produced  very 
satisfactory  remits,  forming  a cheap  white  paint, 
which  can  be  eisily  transferred  with  a brush. 

Many  niinerd  colors,  mixed  with  white  bases,  pro- 


116 


SILICATE  PAINTING  ON  STONE. 


duce  such  difficulties  on  account  of  their  drying  too 
quick,  others  too  slowly,  according  to  the  behavior 
of  the  bases  to  the  soluble  glass.  Many  combinations 
retain  the  alkali  obstinately,  and  it  was  attended  with 
many  difficulties  to  apply  the  colors  with  the  liquid 
silica;  yellow  ochre,  blue  and  green  ultramarine,  sul- 
phuret  of  cadmium,  peroxide  of  manganese,  the  oxide 
of  chrome,  have  proved  to  unite  well  with  the  silica. 

The  painting  on  stone  is  much  easier  when  silica 
has  been  used  on  the  stone  than  on  that  where  it  was 
not  applied,  for  the  reason  that  the  absorbing  quality 
of  the  silica,  serving  a binding  material,  withdraws 
it  from  the  color,  and  it  is  therefore  very  advisable 
to  apply  several  times  the  liquid,  and  exposing  to  the 
atmosphere  before  applying  the  paint.  A single  silicifi- 
cation  of  the  wall  is  indispensable  on  the  painted 
coloring,  which  is  done  by  preparing,  as  usual^  with 
the  liquid  silica,  as  other  paints  are  treated.  The 
soda  silicate,  used  for  painting  on  walls,  is  easily 
effected  by  the  use  of  the  syringe.  The  painting  on 
walls  is  attended  with  some  difficulty  likew/se,  for 
while  that  on  stone  remains  unaltered,  the  wood  is 
apt  to  shrink,  or  to  crack,  and  many  woods  will  not 
easily  take  the  paint,  and  even  change  they  physical 
appearance,  becoming  darker;  oak  wood  assumes  the 
appearance  of  an  old  wood,  and  only  ti^  white  and 
hard  woods,  such  as  the  ash  and  maply^ woods,  will 
take  up  the  silicate  painting.  Another  dfficulty  takes 
place  in  painting  on  wood,  that  it  peelsoff,  if  applied 
too  thickly.  A weak  solution  of  1 paic  silica,  of  28° 
B.  to  5 parts  water,  either  alone  or  iombined  with 
other  bodies,  is  recommended. 

The  new  art  of  painting— Stereo-clromic— derives 


SILICATE  PAINTING  ON  STONE. 


117 


its  names  from  two  Greek  words,  crepeoff,  fast,  or  per- 
manent, and  from  the  color,  and  has  been 

introduced  as  a substitute  for  fresco  painting,  and  bids 
fair  to  be  very  extensively  applied,  and  more  than  the 
encaustic  painting,  from  the  fact  that  the  works  exe- 
cuted by  this  art  have  given  great  satisfaction  ; the 
inner  halls  of  the  new  museum  at  Berlin  have  been 
painted  by  Kaulbach  with  panels  21  feet  high  and  24f 
feet  broad,  and  are  said  to  equal  the  oil  paintings  in 
freshness  and  vigor,  and  with  that  particular  ad- 
vantage, that  the  paintings  may  be  viewed  or  examined 
from  a certain  stand  to  do  so,  and  that  it  may  be 
applied  on  many  grounds  without  the  rough  mortar 
being  first  used.  An  experiment  was  made  to  expose 
a painting  for  one  year  to  the  atmospheric  air,  to  the 
sun,  fog,  snow  and  rains,  and  retaining  during  the 
whole  time  its  freshness.  An  important  circumstance, 
however,  is  the  formation  of  the  groundwork,  for  any 
neglect  in  that  of  the  lower  and  upper  ground  mate- 
rially affects  the  beauty  of  the  painting.  In  order  to 
produce  a uniform  strong  firmness,  it  is  necessary  to 
supply  the  soluble  glass  uniformly,  so  that  it  may  be 
absorbed  perfectly  and  uniformly. 

The  walls  must  be  well  cleansed,  in  the  first  in- 
stance, when  the  mortar  is  laid  on,  and  then  a weak 
solution  of  the  liquid  glass  is  passed  over  it  and  left 
to  dry.  Clean  washed  sand  or  limey  sand  is  then 
mixed  with  a very  small  quantity  of  burnt  lime,  and 
made  into  a paste  and  laid  on  the  wall.  The  surface  is 
made  even  by  an  instrument,  and  the  upper  layer  re- 
moved which  was  formed  on  coming  in  contact  with 
the  air  ; but  the  mass  must  be  always  kept  moist 
during  the  whole  operation.  This  rough  mortar  will 

G* 


118 


SILICATE  PAINTING  ON  STONE. 


soon  become  dry,  and  may  be  rubbed  off  with  the 
fingers,  but  it  must  not  be  left  too  long  exposed  to  the 
air,  for  fear  of  its  attracting  the  carbonic  acid,  whereby 
the  lime  would  be  too  much  carbonized. 

By  the  application  of  a solution  of  carbonate  of  am- 
monia a considerable  hard  consistency  is  produced, 
when  the  liquid  may  now  be  applied  several  times  with 
a brush,  but  always  at  intervals,  and  enough  to  pene- 
trate into  the  mortar,  and  the  liquid  glass  ought  to  be 
that  made  from  soda,  and  quite  clear.  In  all  cases 
the  liquid  must  be  laid  on  by  means  of  a brush,  in 
order  to  produce  a uniform  impregnation  of  the  same. 
When  this  groundwork,  called  the  underground,  is 
faithfully  and  carefully  prepared,  the  upper  ground- 
work which  is  to  receive  the  painting  may  be  com- 
menced with ; it  does  not  differ  much  from  the  first 
operation. 

The  sand  to  be  used  must  be  of  fine  grain,  and  well 
washed,  as  also  the  quartz,  etc.,  (the  lime  sand,)  which 
is  obtained  from  marble  or  dolomite,  finely  powdered, 
are  to  be  used  to  the  thickness  of  one  line  quite 
evenly,  in  order  to  obtain  the  necessary  roughness  on 
the  surface  indispensable  to  the  process  of  painting. 
It  may,  perhaps,  be  necessary  to  use  other  substances 
before  the  application  of  the  fine  sand,  in  order  to 
destroy  any  lime  crust  which  might  have  been  formed 
in  the  preparation  of  underground,  and  diluted  phos- 
phoric acid  is  now  recommended  to  be  applied  with  a 
sponge  or  brush  on  its  surface,  for  it  forms  then  a 
phosphate  of  lime  with  the  soluble  glass,  which  binds 
well  and  does  not  injure  the  mortar.  The  ground  so 
prepared,  and  well  dried,  is  now  impregnated  with  the 
liquid  glass,  the  same  as  the  first,  and  dilated  also 


SILICATE  PAINTING  ON  STONE. 


119 


with  equal  quantities  of  water,  which  is  done  twice, 
allowing  sufficient  time  to  dry  between  each  impreg- 
nation. 

Wood  may  be  painted  by  covering  it  first  with  a 
chalk  ground,  which  must  be  thick  enough  to  allow 
a polishing  with  pumice ; to  chalk,  glue  or  a little 
silicate  solution  may  be  added,  as  a binding  material. 
Another  difficulty  occurs  after  the  first  has  been  over- 
come, in  the  oozing  out  of  the  carbonate  of  potash  in 
damp  weather,  until  the  whole  salt  has  been  expelled, 
and  many  experiments  have  failed,  and  hydrochlorate 
of  ammonia  was  first  proposed  in  a weak  solution,  and 
an  absolute  insolubility  of  the  color  was  thereby  ob- 
tained, but  chlorate  of  potash  remained  in  this  opera- 
tion, which  destroys  the  gloss  of  the  colors  if  not  at 
once  removed  by  repeated  washing  ; forced  to  resort 
to  those  few  chemical  agents,  apt  to  fix  the  potash, 
which  should  enter  as  insoluble  combinations  in  the 
color  without  destroying  them,  the  perchloric  and 
hydrofiuoric  acids  were  resorted  to.  It  is  well  known, 
that  by  washing  with  hydrofiuoric  acid  the  den  sit}"  of 
the  colors  is  much  increased,  and  it  was  thought^ 
therefore,  safe  to  use  it,  particularly  in  painting  on 
glass,  but  only  as  a very  weak  solution.  Hydrofluoric 
acid  possesses  the  most  remarkable  property  to  dis- 
solve most  oxides  when  in  a concentrated  state.  The 
application  of  the  weak  solution  of  hydrofluoric  acid, 
either  for  fixing  the  potash  in  painting  and  in  silicifi- 
cation  of  limestone,  was  mainly  calculated  for  such 
case  where  a silicate  has  been  used  with  an  excess  of 
potash  ; and  in  hardening  of  soft  and  porous  limestones 
by  a partial  conversion  into  a lime  silicate,  it  was 
found  very  expedient  for  fixing  the  potash,  and  making 


120 


SILICATE  PAINTING  ON  STONE. 


sure  the  insolubility  to  moisten,  at  first  with  a weak, 
and  then  strong  solution  of  the  hydrofluoric  acid,  the 
stones  when  the  potash  oozed  out.  The  acid,  however, 
penetrates  the  stone  and  produces  an  insoluble  com- 
pound ; in  other  words,  it  fixes  the  soluble  potash,  and 
produces  an  insoluble  compound.  Through  this  dis- 
covery hydrofluoric  acid  was  found  a very  useful 
application  in  the  fluosilicated  lime. 

If  brought  in  contact  with  lime,  hydrofluoric  acid 
is  capable  of  dissolving  it  considerably  without  pro- 
ducing an  immediate  precipitate  of  calcium,  or  a 
separation  of  the  silica;  but  at  a certain  state  of  satu- 
ration any  addition  of  lime  decomposes  entirely  the 
hydrofluoric  acid,  and  so  much  that  not  a trace  of 
these  bodies  can  be  discovered  in  the  fluid.  The  same 
results  are  obtained  by  the  carbonate  of  lime,  instead 
of  the  caustic  lime,  and  that  silicium  and  fluor  are 
produced  in  the  limestone,  which  hardens  but  slowly, 
and  it  is  therefore  simply  a fluorsilicon  that  produces 
the  hardening  of  the  lime.  The  effect  of  the  hydro- 
fluoric acid  on  gypsum  is  also  produced  in  both 
mixing,  the  surface  of  the  gypsum  is  considerably 
hardened.  If,  however,  the  acid  is  used  in  excess,  the 
gypsum  is  covered  with  raised  pustules,  which  owe 
their  existence  to  the  formation  of  bisulphate  of  lime, 
because  sulphuric  acid  does  not  act  as  well  as  the  car- 
bonic acid  in  the  treatment  of  limestone  ; a fluor- 
calcium,  mixed  with  soluble  glass,  may  be  used  as  a 
paint,  or  paste,  or  a cement,  or  any  coating  of  other 
substances,  and  becomes  so  hard  and  weatherproof 
that  neither  soda  nor  potash  will  detach  from  the 
cumbination,  and  will  remain  dry. 


SILICATE  PAINTING  ON  STONE. 


121 


Painting  on  Metals,  - Glass  and  Porcelain. 

Silica  painting  adheres  strongly  on  metals,  pro- 
vided care  is  taken  to  keep  the  substances  some  time 
from  the  contact  with  water.  The  most  durable  paint 
is  produced  on  zinc,  also  on  porcelain  and  glass  ; the 
colors  assume  a semi-transparency  if  painted  on  glass, 
and  no  doubt  afford  much  inducement  for  its  use. 
The  sulphate  of  baryta,  artificially  prepared,  com- 
bined wfith  silicate,  applied  to  glass,  makes  a milky 
white  appearance,  and  is  very  beautiful,  as  it  incor- 
porates very  intimately  with  the  silica,  so  that  after 
the  lapse  of  a few  days  the  paint  cannot  be  removed 
even  with  warm  water.  If  this  glass  is  exposed  to 
high  heat,  (6°  Wedgewood,)  a fine  white  enamel  is 
formed  on  the  surface,  which  will  compare  well  with 
the  oxide  of  tin,  and  is  much  cheaper.  Ultramarine, 
’oxide  of  chrome,  if  converted  into  enamels,  form  a 
prolific  source  for  the  new  art  of  painting.  It  is  not 
quite  necessary  that  a chemical  combination  should 
be  produced  in  all  these  colors,  if  they  only  adhere 
strongly  and  produce  the  silicated  cement,  which  has 
become  hard  by  its  fine  division  and  easy  admission 
of  air. 

Emery,  bloodstone,  and  peroxide  of  manganese,  if 
finely  powdered  and  prepared  with  a concentrated 
solution  of  soluble  glass,  produce  cements  of  extraor- 
dinary^ hardness,  resisting  the  effect  of  heat  complete- 
ly, and  become  perfectly  insoluble  in  water. 

For  the  production  of  an  indestructible  ink,  soluble 
glass  has  been  used  and  obtained  by  mixing  finely 
burnt  lampblack  with  the  liquid  soluble  glass.  Bra- 
connofs  ink  is  prepared  by  decomposing  leather  in 


122 


SILICATE  PAINTING  ON  STONE. 


caustic  potash,  and  adding  to  the  black  mass  the  liquid 
soluble  glass.  A decoction  of  cochineal  mixed  with 
the  liquid  soluble  glass,  produces  a red  ink,  resisting 
completely  the  action  of  chlorine  and  all  other  acids. 

Stereo-chromig  for  Easel  Painting. 

The  basis  for  this  class  of  painting  may  be  made 
from  plates  of  burnt,  porous  clay  ; it  is  first  impreg- 
nated sufficiently  with  liquid  soda  glass.  These  plates 
may  be  three-fourths  of  an  inch  thick ; after  one  or 
two  applications  they  become  as  hard  as  any  stone 
ware ; they  are  very  suitable  for  painting  ground. 
The  lithographic  stone  makes  a good  base  for  easel 
painting ; a thin  coating  of  liquid  glass  mortar  will 
produce  a good’  base,  and  it  may  be  first  moistened 
with  phosphoric  acid,  which  assists  much  to  absorb 
the  colors  with  the  liquid  glass,  and  to  make  them  fast. 

The  colors  to  be  used  for  this  class  of  painting 
ought  not  to  be  chosen  which  decomposes  the  liquid 
glass,  such  as  contain  strong  acids,  nor  those  from 
organic  substances.  Burnt  oxides  are  better  than 
raw  oxides,  vermilion  becomes  brown,  and  at  last 
black ; cobalt  blue  becomes  clearer  by  the  liquid, 
and  the  yellow  ochre  becomes  darker. 

All  colors  ought  to  be  properly  prepared  to  make 
them  fit  for  the  silica  painting,  such  as  the  great 
variety  of  oxides ; many  of  which,  not  containing 
much  oxide  of  iron,  may  be  suitable,  also  chrome  red, 
ultramarine,  umber,  baryta  white,  cadmium  yellow, 
and  many  more,  purposely  made  by  some  chemists, 
not  containing  free  acid,  which  enter  into  a decom- 
posing chemical  combination. 


SILICATE  PAINTING  ON  STONE. 


123 


The  permanent  white,  or  artificial  sulphate  of 
barj^ta,  is  said  to  be  the  proper  material  for  a white 
paint.  It  is  obtained  from  the  native  minerals, 
heavy  spar  or  sulphate  of  baryta,  and  witherite  or 
carbonate  of  baryta.  The  manufacture  of  the  new 
paint  is  efiected  by  the  reduction  of  the  native  sul- 
phate to  a chloride  of  barium,  or  dissolving  the  native 
witherite  in  hydrochloric  acid,  and  then  adding  either 
sulphuric  acid  or  glaubersalt;  the  artificial  sulphate  of 
baryta  is  found  in  a condition  of  extreme  fineness  and 
purity,  possessing  a fine  lustre,  and  susceptible  for 
producing  a fine  white  paint,  which  is  the  best  substi- 
tute for  white  lead  and  zinc  white,  is  not  subject  to 
tarnish  or  become  brown  in  parlors  like  white  lead, 
which  is  attacked  by  hydrosulphuric  acid,  and  forms, 
when  combined  with  the  liquid  glass,  a slow  but  inti- 
mate combination,  and  is  likewise  used  under  the 
name  of  blancfix  for  card-makers,  paper-stainers  and 
paper  collar  manufacturers  to  a very  large  extent.  It 
may  also  be  considered  in  point  of  importance,  if  com- 
pared  with  that  of  white  lead,  not  having  a dilatory 
effect  upon  health  as  the  latter.  If  mixed  with  the 
soluble  glass  it  obviates  the  odious  smell  of  linseed  oil 
and  spirits  of  turpentine.  If  it  is  mixed  with  dexter- 
ine,  starch,  or  other  binding  material  in  connection 
with  the  liquid  silicate  of  soda,  its  applications  may 
be  multiplied  to  any  extent. 

The  artificial  sulphate  of  baryta  is  largely  manufac- 
tured on  the  continent  of  Europe;  in  the  United 
States  it  has  so  far  been  manufactured  in  New- York 
by  a few  chemical  establishments  for  card  makers, 
but  not  yet  for  the  purpose  of  substituting  it  to  white 
lead. 


SILICIFlCiTION  OF  WOOD. 


A PROTECTION  AGAINST  CoMBUSTION,  INFLAMMABILITY 

AND  Dry  Rot. 

Wood,  and  all  other  organic  combustible  substances, 
may,  to  a great  extent,  be  preserved  against  that  great 
element,  the  fire,  by  the  proper  application  of  the  liquid 
silicates.  Still  it  requires  much  skill,  experience  and 
proper  management  to  subdue  totally  this  wonderful 
element  when  brought  to  its  full  power.  There  are 
many  instances  on  record  to  prove  either  a full,  or  at 
least  partial  success  in  arresting  the  progress  of  a con- 
fiagration  by  the  impregnation  or  coating  of  combus- 
tible bodies  with  many  substances,  such  as  possess 
incombustibility,  whether  liquids,  gases,  or  materials 
which  possess  the  properties  of  generating  gases,  that 
will  withdraw  or  sulfocate  the  surrounding  atmosphere, 
such  as  the  oxygen  gas,  and  thereby  arrest  the  progress 
of  the  flames.  Many  chemical  agents  have  been  from 
time  to  time  proposed  to  effect  this  object ; such  as  salt, 
chloride  of  lime,  and,  latterly,  carbonic  acid  in  its 
gaseous  and  liquid  form,  and  many  metallic  salts  have 
proved  but  a partial  success  in  the  prevention  of  decay 
. or  dry  rot  of  wood.  The  soluble  glass  is  one  of  the  first 
materials  which  have  been  successfully  employed  in 
arresting  conflagration,  and  as  far  as  1823  this  mate- 
rial was  recommended  in  the  construction  of  the  Mu- 
nich Theatre,  where  465,000  square  feet  of  timber 


SILICIFIOATION  OF  WOOD. 


125 


surface  were  treated  with  a coating  of  the  liquid  solu- 
ble glass,  and  in  1830-31  and  ’32  the  author  per- 
formed many  experiments  in  the  Brooklyn  Navy  Yard, 
partially  as  a protecting  agent  against  fire,  as  also 
against  decay  of  the  woody  fibre.  Small  square  blocks 
of  wood,  after  having  been  impregnated  with  the  solu- 
ble glass,  and  sailcloth,  writing  paper,  parchment,  etc., 
were  exposed  for  some  time  to  the  flame  of  a gas  lamp. 
After  the  lapse  of  an  hour,  all  these  substances  were 
found  to  be  charred,  but  not  consumed.  It  is  proved 
that  the  liquid  soluble  glass  produces  a perfect  ad-- 
hering,  permanent  covering  which,  when  properly  laid 
on,  suffers  no  damage  from  the  atmosphere.  For 
coating  the  wood,  etc.,  a pure  solution  of  the  liquid 
glass  is  required,  otherwise  it  will  peel  off,  and  it  is 
best  not  to  use  it  first  in  a concentrated  state,  as  it 
will  not  be  able  to  penetrate  into  the  pores,  whereby 
the  atmosphere  must  be  expelled,  and  even  five  or  six 
applications  may  be  made  in  intervals  of  twenty-four 
hours.  Although  this  process  renders  good  services, 
it  may  be  improved  by  the  addition  of  other  pulver- 
ized substances,  wherein  the  soluble  glass  acts  as  the 
binding  material,  the  coating  assumes  a better  body, 
is  stronger  and  more  permanent,  and  if  exposed  to 
the  fire,  a crust  is  formed  ; such,  for  instance,  are  bone 
dust,  clay  and  chalk  mixed  together,  a lead  glass,  etc. ; 
common  clay,  one-tenth  of  the  quantity  of  silicate  of 
soda,  was  successfully  used  with  the  liquid  glass  in  the 
Munich  Theatre.  If  applied  on  linen  or  other  organic 
textures,  the  mere  coating  or  dipping  is  not  sufficient, 
but  a surface  between  rollers  must  be  resorted  to,  in 
order  to  produce  a full  absorption  with  the  pores  ; 
these  stuffs  may  then  be  rolled  up,  but  not  folded. 


126 


SILICiriCATION  OF  WOOD. 


Building  timber,  rail-road  sleepers,  and  other  simi- 
lar materials,  have  been  treated  in  the  manner  just 
described,  and  were  protected  fully  against  fire  and 
dry  rot. 

The  author  proposed  a combination  of  the  liquid 
glass  with  the  following  substances,  intended  as  de- 
composing agents  by  chemical  affinity,  and  producing 
in  the  cells  of  the  vegetable  fibre  the  various  min- 
eral and  metallic  salts  which  are  altogether  insoluble 
in  water,  alkalies  and  acids,  and  he  extended  his  ex- 
periments on  the  uses  of  lime,  chalk,  gypsum,  cop- 
peras, etc.  His  process  of  treating  ship  timber, 
sleepers,  cross-ties,  roofing  shingles  and  other  ^ wood 
blocks  was  the  following  : 

1.  The  materials  to  be  treated  were  put  in  steam 
boilers  and  exposed  for  four  hours  to  a pressure  of 
hot  steam,  (or  300°  F.,)  then  withdrawn  from  the  ket- 
tles and  dried.  Alkalies  and  acids,  such  as  hydro- 
chloric, have  been  since  recommended  for  the  purpose 
of  abstracting  color  and  albumen  existing  in  the  cells 
of  the  woody  fibres,  which,  however,  is  accomplished 
by  steaming. 

2.  In  a solution  of  silicate  of  soda  while  hot,  the 
materials  to  be  treated  are  thrown  and  kept  there  for 
twenty-four  hours,  which  will  give  ample  time  for  the 
liquid  to  enter  into  the  open  cells  while  hot. 

3.  A large  vat,  containing  either  lime  water,  solu- 
tion of  copperas,  or  blue  vitriol,  white  vitriol  or  gyp- 
sum, finely  powdered,  and  thrown  into  hot  water,  or 
finely  powdered  chalk  of  1 pound  to  10  gallons  of 
water;  the  proportion  of  metallic  salts  is  but  one- 
quarter  pound  to  the  gallon  of  water.  The  woods  are 


SILICIFICATION  OF  WOOD. 


127 


kept  in  the  vats  for  another  day,  and  then  taken  out, 
dried  and  ready  for  use. 

Coal  tar,  and  the  other  products  of  dry  distillation 
from  tar  and  peat,  have  been  recommended  by  Krieg 
as  far  back  as.  1858,  under  the  name  of  Creosote-car- 
bolic acid,  which  was  then  considered  a waste  product, 
and  in  its  raw  state  having  a specific  gravity  of  1.02 
to  1.05^,  and  yielded  from  20  to  30  per  cent,  of  the 
tar;  it  was  well  known  to  possess  the  property  of  pro- 
tecting wood  against  decay. 

This  chemist  combined  with  the  impregnation  of 
woods,  etc.,  the  soluble  glass  and  the  creosote-car- 
bolic acid,  for  the  reason  that  the  latter  precipitates 
the  soluble  silica  as  an  insoluble  substance  while  it  is 
soluble  in  an  alkaline  lye.  He  proposed  to  expose  the 
woods  for  three-quarters  of  an  hour  to  a temperature 
of  300°  F.,  and  then  drying  them  thoroughly. 

The  woods  thus  prepared  showed  an  increased 
weight  of  6 per  cent.,  and  a lacquered  surface,  while 
in  the  inside  the  pores  were  filled  with  an  insoluble 
precipitated  silica. 

For  effecting  a still  more  perfect  success  is  to  fix 
the  creosote  on  the  woody  fibre  from  the  alkaline  solu- 
tion, by  diluted  sulphuric  acid,  or  by  a solution  of 
copperas,  (sulphate  of  iron,)  whereby  the  sulphate 
of  soda  thus  obtained  may  either  be  washed  out, 
or  oozed  out,  the  creosote-carbolic  acid  combines 
stronger  with  the  woody  fibre,  and  the  impregnated 
woods  may  be  considered  safely  protected  against  fire 
or  rot. 

This  process  just  described,  deserves  the  serious  at- 
tention of  the  various  companies  established  for  the 
last  five  years  in  the  preservation  of  wood  by  carbolic 


128 


SILICIFIOATION  OF  WOOD. 


acid,  tar,  etc.,  by  combining  the  soluble  glass  with 
their  process,  as  we  have  described. 

Since  the  introduction  of  rail-roads,  not  quite  50 
years,  many  men  have  been  engaged  in  chemical  ex- 
periments upon  the  cross-ties  and  sleepers,  which, 
after  being  laid  down  for  a few  years,  undergo  the  de- 
cay or  rot,  and  have  to  be  renewed,  which  causes 
great  expense  to  the  companies.  Kyan,  Burnett, 
Laboucheri,  and  many  other  chemists  in  all  countries 
where  this  evil  existed,  proposed  remedies;  the  subli- 
mate, chloride  of  zinc,  pyrolignite  of  iron,  all  had  their 
advantages  and  disadvantages  ; of  late,  borax,  alum, 
rosin,  carbolic  acid  have  been  introduced. 

Wooden  Hoof  Shingles. 

One  of  the  most  valuable  applications  of  the  soluble 
glass  may  be  recommended  for  shingles  and  wooden 
roofs  of  farm-houses  in  the  country  and  near  rail-roads, 
where  the  sparks  of  the  locomotives  have  frequently 
caused  conflagrations  and  destruction  of  property. 

The  operation  is  quite  simple,  and  the  expense 
but  trifling ; the  process  has  already  been  described, 
but  it  may  be  still  more  simplified  in  the  following 
manner : 

After  the  steaming  of  the  shingles  in  boilers  or  in 
tanks,  where  steam  of  250  to  350°  is  led  into  them, 
they  are  dried  and  thrown  into  a weak  solution  of 
liquid  silica,  standing  about  25°  B.,  in  which  they  are 
left  for  twenty- four  hours,  when  they  are  taken  out 
and  exposed  to  the  air.  Before  they  are  quite  dry,  a 
weak  solution  of  chloride  of  calcium  is  thrown  over 
them  or  sprinkled  over  them  with  a broom.  When 


SILICIFIOATION  OF  WOOD. 


129 


quite  drj  they  are  fit  for  use.  They  will  uot  burn 
nor  be  ignited  with  the  sparks  ; if  exposed  to  a direct 
fire,  will  not  light  in  a surrounding  fire.  An  intense 
heat  of  long  duration  may  char  them  on  the  surface  ; 
they  are,  however,  quite  safe  from  any  inflammation. 

The  Preservation  of  Wood  by  Immersion. 

The  processes  for  the  preservation  of  wood  may  be 
divided  into  three  groups,  namely  : processes  by  im- 
mersion ; processes  by  pressure  in  closed  vessels, 
(which  are  exclusively  employed  for  dry  wood,)  and 
processes  founded  on  the  displacement  of  the  sap, 
(which  are  only  employed  for  green  wood.)  In  the 
present  article  we  shall  describe  the  methods  by  im- 
mersion. 

Attempts  to  impregnate  wood  by  the  method  of 
immersion  were  the  first  experiments  undertaken. 
As  early  as  1740,  Fagol,  a Frenchman,  tried  to  im- 
pregnate wood  with  alum,  sulphate  of  iron,  and  vari- 
ous other  substances,  in  solutions  of  which  he  im- 
mersed it  for  several  days.  In  1756,  Haller  recom- 
mended vegetable  oil  for  the  same  purpose.  In  1767, 
Jackson  indicated  the  use  of  a solution  of  sea  salt,  to 
which  sulphate  of  iron  and  magnesia,  alum,  lime  and 
potassa  were  to  be  added.  In  1779,  Pallas  proposed 
to  mineralize  wood  by  dipping  it  first  in  a solution  of 
green  copperas  and  afterward  in  milk  of  lime.  In 
1830,  Kyan,  in  England,  tried  to  preserve  wood  by 
simply  immersing  it  in  a solution  containing  two  per 
cent,  of  bichloride  of  mercury.  Hot  long  since,  ex- 
periments were  made  in  France  and  Germany  with  a 
large  number  of  rail  road  ties,  by  keeping  them  several 


130 


SILICIFIOATION  OF  WOOD. 


Lours  in  a solution  containing  1.5  per  cent,  of  sulphate 
of  copper,  at  a temperature  of  160°  Fahr.  This  pre- 
paration is,  however,  altogether  insufficient  for  the 
preservation  of  fir  or  pine  wood,  and  in  general  for 
light  woods  which  contain  a large  amount  of  nitro- 
genous substances  ; but  it  seems  to  increase  considera- 
bly the  durability  of  oak.  The  wood  is  thus*^  sur- 
rounded by  a very  thin  coating,  which  is  not  liable  to 
decay  nor  to  the  attacks  of  insects,  and  which  retards 
the  alteration  of  the  inner  parts.  These  are,  however, 
not  iinpregnated  at  all  by  the  antiseptic  liquid ; they 
preserve  their  germs  of  putrefaction,  which  develop 
the  easier  the  more  the  injected  surface  is  removed, 
whether  by  friction,  blows,  or  the  driving  in  of  nails. 
The  decay  commences  then  at  the  denuded  points, 
and  propagates  itself  toward  the  central  parts. 

Decay  of  Wood  and  Processes  for  Preserving  it. 

According  to  the  experiments  which  were  made  by 
De  Saussure,  in  the  beginning  of  this  century,  it 
would  seem  that  the  decay  of  woody  fibre  was  exclu- 
sively caused  by  the  action  of  air  and  water.  On  ex- 
posing moist  wood  to  the  action  of  oxygen  gas,  he 
found  that,  for  every  volume  of  oxygen  absorbed  by 
the  wood,  one  volume  of  carbonic  acid  was  disengaged. 
It  is  now  conceded  that  it  is  the  hydrogen  of  the  fibre 
which  is  oxydized  at  the  expense  of  the  oxygen  of  the 
atmosphere,  while  the  carbonic  acid  is  solely  formed 
from  the  elements  of  the  wood,  or  that  the  process  is 
simply  a separation  of  a portion  of  the  carbon  of  the 
wood  by  direct  oxydation  ; and  it  would  seem,  from 
the  experiment  mentioned,  that  the  first  and  only 


SILICIFICATION  OF  WOOD, 


131 


cause  of  the  decay  of  vegetable  tissue  must  be  ascribed 
to  the  affinity  of  oxygen  for  the  elements  of  the 
latter. 

Such  cases  of  slow  decomposition  have  indeed  also 
been  distinguished  by  the  name  eremacausis^  a term 
composed  of  two  Greek  words,  and  meaning  to  burn 
by  dt3grees. 

The  above  explanation,  however,  scarcely  holds 
good  in  all  cases;  it  is  now  known  that,  in  dry  air, 
woody  fibre  may  be  preserved  without  decaying  for 
thousands  of  years  ; and,  under  water,  in  certain  con- 
ditions, it  appears  to  be  equally  durable.  One  must, 
therefore,  look  for  some  other  cause  to  explain  the 
transformation  of  vroody  fibre.  Such  a one  presents 
itself  in  the  fact  that,  when  wood  is  exposed  for  some 
weeks  to  running  water,  or  if  it  is  boiled  in  water  and 
afterwards  dried  until  the  original  weight  is  restored, 
it  is  rendered  thereby  considerably  more  durable. 

The  cause  of  the  transformation  in  question  must, 
therefore,  be  sought  in  a substance  which  is  removed 
by  the  dissolving  action  of  water  in  the  experiment 
mentioned.  By  further  investigation,  this  substance 
is  found  to  consist  of  the  albumen  of  the  sap,  which  is 
distributed  throughout  the  cellular  tissue.  Like  the 
animal  albumen,  as  the  white  of  eggs,  which  it  closelj^ 
resembles  both  in  properties  and  composition,  the 
vegetable  albumen  is  exceedingly  liable  to  decomposi- 
tion. In  this  state  it  acts  like  a ferment,  inducing 
the  decay  of  other  bodies,  according  to  the  physical 
law  propounded  in  another  application  by  Laplace 
and  Berthollet,  namely,  that  a molecule  set  in  m'o- 
tion  by  any  power  can  impart  its  own  motion  to 


132 


SlLIClFICATlON  OF  WOOD. 


anotlier  molecule  with  which  it  may  come  in  con- 
tact. 

Among  the  bodies  most  prone  to  decomposition  is 
the  sugary  element,  which  is  first  dissolved.  Then 
the  growth  of  fungi  generally  begins,  and  the  putre- 
faction proceeds  step  by  step.  It  may,  therefore,  be 
considered  that  the  spontaneous  decomposition  of  the 
vegetable  albumen  is  the  primary  cause  of  the  decay 
of  wood.  It  is,  indeed,  found  that  those  kinds  of 
wood  which  contain  the  smallest  quantity  of  albu- 
minous matter  and  amylum  are  the  most  durable. 
Especially  is  this  the  case  with  a certain  tree  of  the 
acacia  tribe,  the  locust,  and  the  cedar,  which  resist 
decomposition  in  situations  where  all  other  kinds  of 
wood  soon  decay. 

In  order,  then,  to  find  out  whether  a certain  kind  of 
wood  is  especially  fitted  for  building  purposes,  the 
quantity  of  albumen  present  in  the  fibre  should  be 
ascertained  by  analysis.  M.  Payen  recommends,  for 
this  purpose,  to  digest  the  wood  in  a dilute  solution 
of  caustic  alkali — this  soda,  or  potassa — which  has  no 
action  on  the  woody  fibre,  but  only  dissolves  the  albu- 
men. Hence  the  quantity  of  the  latter  may  be  esti- 
mated by  washing,  drying  and  weighing  the  wood 
after  the  experiment  has  been  made. 

Hipregnation  of  Wood  by  Pressure. 

The  apparatus  now  used  in  France  for  the  satura- 
tion of  timber  with  preservative  agents  is  described  as 
follows  : It  consists  of  a cast-iron  cylinder,  which  is 
connected  by  means  of  a tube  with  a condenser.  Both 
are  placed  in  a vertical  position.  The  operation  is 


SILICIFICATION  OF  WOOD. 


133 


begun  by  introducing  the  timber  into  the  cast-iron 
cylinder,  together  with  the  preservative  material.  The 
latter,  however,  is  not  altogether  to  rise  to  the  entire 
height  of  the  stem.  The  receptacle  of  the  wood  is 
hereupon  closed,  and  connected  with  the  condenser. 
A vacuum  is  then  produced  in  the  latter,  which  is 
accomplished  by  introducing  alternate  steam  and 
sprays  of  water  into  it.  After  this  the  stop-cock  of 
the  tube  connecting  the  two  cylinders  is  opened,  when 
the  air  passes  from  the  receptacle  into  the  condenser. 
This  operation  is  repeated  until  the  pressure  in  the 
cylinder  is  less  than  fifteen  decimetres.  The  same  is 
kept  up  for  several  minutes,  in  order  to  let  the  air  of 
the  timber  have  time  to  escape.  The  connection  be- 
tween the  receptacle  and  the  condenser  is  finally 
closed.  A pump  is  then  set  in  motion,  by  means  of 
which  the  preservative  agent  is  made  to  penetrate  the 
pores  of  the  vegetable  tissue,  until  the  pressure  stands 
at  that  of  ten  atmospheres.  This  is  maintained  for 
various  lengths  of  time,  according  to  the  nature  of  the 
wood  and  the  liquid,  but  six  hours  are  generally 
sufficient.  After  this  the  air  is  gradually  allowed  to 
enter,  while  the  preservative  liquor  is  left  to  run 
away. 

“ The  capability  of  wood  to  sustain  the  strain  to 
which  it  must  necessarily  be  exposed,  especially  when 
moving  over  it  at  high  velocities,  has  been  satisfac- 
torily proved  by  the  experience  of  the  Great  Western 
and  other  railways,  where  continuous  longitudinal 
sleepers  of  wood  have  been  employed,  and  experience 
has  shown  that  the  solidity  of  the  road  is  much 
greater  than  when  the  iron  rails  were  attached  either 
to  stone  locks  or  transverse  wooden  sleepers.  In 


134 


SILIcmCATION  05’  WOOD. 


proof  that  wooden  rails  cut  from  beech  will  hear  the 
wear  and  tear  of  trains  passing  over  it,  it  is  well  known 
that  beech  cogs  have  proven  to  last  eighteen  to  twenty 
years  when  working  in  gear  with  an  iron  wheel.  The 
rails  on  the  Yauxhall  line  were  prepared  by  Payne’s 
patented  process  for  preventing  dry  rot  and  decay  of 
timber.  Scotch  fir,  if  subjected  to  pressure,  will  crush 
at  ten  tons,  while  beech  (the  wood  recommended  for 
railways)  will  bear  a pressure  of  eighty -two  tons  before 
it  begins  to  yield. 

“ Experience  having  confirmed  the  capability  of 
Scotch  fir  to  withstand  the  traffic  of  twelve  engines 
per  day  for  seven  years,  without  any  visible  wear,  it 
wmuld  be  difficult  to  say  how  long  the  rails  cut  from 
beech,  sustaining  eighty-two  tons  pressure,  would  last. 
Some  of  the  impediments  with  which  rail-roads  have 
to  contend  are  the- undulations  of  the  country,  and 
the  necessity  of  diverging  from  a right  line  in  order  to 
obtain  the  traffic  of  important  towns.  These  obstacles 
can  only  be  overcome  by  an  outlay  of  capital,  in 
making  the  required  excavations  and  embankments,  or 
by  the  oftentimes  ruinous  system  of  tunnelling ; and 
after  all,  inclines  of  greater  or  less  gradients  are  una- 
voidable, and  prevent  the  line  working  economically. 
Curves  on  iron  rail-roads  are  highly  prejudicial,  espe- 
cially if  the  radius  be  small,  as  the  wear  and  tear  be- 
comes proportionably  increased.” 

Timber  Kot  and  Seasoning. 

It  is  generally  supposed  that  the  rotting  of  timber 
is  merely  induced  by  the  action  of  the  oxygen  of  the 
air.  From  analysis  made  of  sound  and  decayed  oak, 


SILICIFICATION  OF  WOOD. 


135 


it  has  been  shown  that  for  every  two  equivalents  of 
liydrogen  oxjdized  by  the  air,  one  equivalent  of  car- 
bonic acid  had  separated.  It  may  therefore  be  in- 
ferred that  the  decay  or  rot  of  timber  does  not  arise 
from  fermentation,  but  is  rather  a chemical  process. 
Others  admit  that  microscopical  parasites  of  vege- 
table nature  play  an  important  part  in  the  deca}^  of 
wood  ; but  consider  tlie  presence  of  albuminous  mat- 
ter in  the  sap  as  necessary,  wliich,  according  to  them, 
must  also  be  first  in  a state  of  decomposition  before  it 
allows  the  growth  of  those  organisms.  In  order  to 
throw  light  upon  this  most  important  subject,  we  pro- 
pose first  to  tabulate  a number  of  well  observed  facts. 
Sound  timber,  when  immersed  in  water,  without  ac- 
cess of  air,  will  withstand  decay  for  almost  an  un- 
limited time.  This  is  proved  by  the  piles  upon  which 
the  dwellings  on  the  Canaries  rest,  which  were  erected 
in  the  time  of  the  Conquest  in  1402,  they  being  just 
as  sound  now  as  if  they  had  been  freshly  felled.  Roots 
of  trees  that  have  been  submerged  in  marshes  are 
rarely  found  decomposed.  This  is  stated  to  be  the 
case  with  the  utensils  discovered  in  the  lake  dwellings 
of  Switzerland,  Bavaria  and  Lombardy,  which  must 
be  at  least  ten  thousand  years  old.  Hartig  also  de- 
scribes a cypress  stem  with  over  three  thousand  rings, 
representing  the  same  number  of  years,  which,  though 
submerged,  had  only  partially  turned  into  brown 
coal. 

With  respect  to  the  action  of  the  atmospheric  air,  it 
may  be  asserted  that  the  same,  even  when  moist,  will 
not  produce  rot  if  the  wood  has  been  well  steamed,  or 
exposed  to  the  action  of  running  water  for  a sufficient 
length  of  time.  In  England  it  is  customary  to  lay  the 


136 


SILICIFICATION  OF  WOOD. 


timber  destined  for  threshing-floors  and  wainscoating 
in  fresh  water  for  several  weeks.  When  again  dry, 
and  not  exposed  to  damp,  such  timber  will  endure  for 
an  incredible  period  of  time. 

This  tends  to  demonstrate  the  fact,  that  the  substance 
which  induces  decay  must  be  foreign  to  the  timber  it- 
self. This  substance  is  the  juice  that  is  chiefly  con- 
tained in  the  vascular  tissue,  which  forms  a link  be- 
tween the  bark  and  the  wood.  The  composition  of 
this  sap  varies  according  to  circumstances,  as  the  va- 
riety of  the  tree,  climate,  season,  ground,  etc.  The 
following  are  analyses  of  the  sap  : 


In  100  Parts. 

Sap  of  Elm  Tree. 
Vanquelin. 

Sap  of  Cow  Tree. 
Solly. 

Dried  Sap  of  Bark  of 
Antiarin  Toxicaria. 
Mulder. 

Albumen, 

S.06  {a) 

16.14 

Dextrin,  

• • • . 

4.37  (6) 

12.34 

Sugar, 

• • • • 

6.31 

Resin, 

• • • • 

20.93 

Galactin 

• • • • 

30.57 

. . . 

Myricin, 

• • • . 

• • • • 

7.02 

Antiarin, 

• • • • 

• • • • 

3.56 

Organic  Substance,  (not  determined,). . . . 

0.10 

• • • • 

.... 

Potassa  with  Organic  Acid, 

0.87 

A • • • 

• . . . 

Carbonate  of  Lime, 

0.10 

• • • • 

.... 

Extractive  Matter  and  Salts, 

• • • • 

.... 

33.70 

Water, 

98.93 

62.00(c) 

.... 

100.00 

100.00 

100.00 

(a.)  Gluten  and  Albumen,  according  to  Solly.  (&.)  Dextrin  and 
Salt,  (c.)  Water  and  Butyric  Acid. 

Remarks. — The  Cow  Tree  {Galactodendron)  is  a native  of  the 
Cordilleras  of  Venezuela ; it  furnishes,  by  incision,  an  enormous 


SILICIFICATION  OF  WOOD. 


137 


quantity  of  a white,  thick  liquid,  which  has  the  taste  and  some  of 
the  qualities  of  a real  cow’s  milk.  The  Antiaris  toxicaria  belongs 
to  the  same  family  as  the  former,  namely,  to  the  nettle-worts,  and 
it  is  singular  that  it  furnishes  a most  deadly  poison,  which  has  been 
the  subject  of  the  most  harrowing  stories.  (Jussieu  ; Elements  of 
Botany) 

Unfortunately  we  possess  only  one  analysis  of  a tree 
indigenous  to  North  America;  however,  the  same 
tends  to  show  that  the  amount  of  albumen,  if  the  non- 
determined  organic  matter  must  be  considered  as  such, 
is  exceedingly  small;  and  with  respect  to  the  other 
trees,  these  analyses  prove  that  the  albumen  does  not 
constitute  the  chief  part  among  the  ingredients  of  the 
juice.  How  unjustifiable  it  is,  therefore,  to  attribute, 
in  every  instance,  the  decay  of  timber  to  the  albumen 
present  in  the  sap,  as  if  it  was  the  only  substance  lia- 
ble to  spontaneous  decomposition,  or  affording  the 
vegetation  of  fungi  and  lichens  ! 

In  regard  to  the  amount  of  sap  and  air  contained  in 
the  oak  and  poplar,  we  possess  the  following  data  from 
Count  Rumford  : 


Wood.  Sap.  Air. 

Oak, 0.39353  0.36122  0.24525 

Poplar, 0.24289  0.21880  0.53831 


The  German  botanist,  Schacht,  in  all  instances  of 
decayed  timber,  has  met  with  fungi  and  lichens. 
The  destruction  of  timber  by  decay,  after  the  same 
has  been  hewn,  must,  therefore,  be  considered  as  being 
produced  bj^  similar  causes  which  brought  on  the  dis- 
ease of  the  vine,  potato,  mulberry  trees,  and  other  cul- 
tivated plants,  which  make  the  years  U45,  ’48,  ’53, 
’57  and  others  for  ever  painful  to  the  memory. 


138 


SILICIFICATION  OF  WOOD. 


That  the  juice  should  be  in  a state  of  decomposition 
before  being  capable  of  generating  those  organisms 
seems  doubtful,  since  this  has  not  been  found  the  case 
in  other  and  well  studied  modes  of  fermentation.  The 
morel,  a species  of  mushroom,  will  also  attack  per- 
fectly sound  wood.  Hand  in  hand  with  the  spread  of 
the  fungi  continues  the  decomposition  of  the  ligneous 
tissue.  Access  to  moisture  and  air,  as  also  a certain 
degree  of  heat,  are  necessary.  In  regard  to  the  air, 
fungi  require  oxygen  for  their  generation.  When  air- 
dried,  steamed,  or  chemically  treated  and  afterward 
dried,  wood  commences  to  rot,  it  is  a sign  that  moist- 
ure has  again  penetrated;  for  it  is  scarcely  to  be  ad- 
mitted, that  in  all  these  cases  the  sap  had  been  entirely 
removed.  Timber  decomposes  the  easier  the  more  sap 
it  contains  ; and  if  green  trees  are  hewn  when  the  ves- 
sels are  overflowing  with  juice,  one  may  look  with  cer- 
tainty for  diminished  durability  of  the  timber.  Tim- 
ber is  not  always  the  more  durable  the  more  dense  it 
is,  but  rather  when  the  even  fineness  of  the  grain  con- 
tinues to  the  pith  of  the  stem. 

The  Roman  historian,  Pliny,  considers  the  resin- 
iferous  woods  as  the  most  durable.  Indeed,  nature 
shows  that  this  is  frequently  the  case.  The  resin ifer- 
ous  red  and  white  pines  of  Oregon  and  California  are 
considered  first-class  ship  timber,  so  much  so  that 
entire  vessels  have  been  constructed  from  the  denser 
qualities.  The  yellow  or  long-leaved  pine,  in  dry  sit- 
uations, is  extremely  durable,  and  is  preferred  to  oak 
of  any  kind,  where  a lighter,  yet  solid  wood,  is  re- 
quired. The  white  or  northern  pine,  which  grows 
abundantly  in  every  northern  State  of  the  Union,  from 
Maine  to  Minnesota,  reaching  often  to  an  altitude  of 


SILICIFICATION  OF  WOOD. 


139 


one  hundred  and  eighty  feet,  with  a diameter  of  six 
feet  or  more,  is  said  to  retain  its  properties  as  long  as 
the  veiy  best  description  of  oak. 

The  proportion  in  which  the  woody  fibre  and  water 
are  to  each  other  is  very  different.  It  varies  accord- 
ing to  the  degree  of  dryness  and  the  nature  of  the 
wood  itself.  According  to  Schubler  and  Neuffer,  we 
have  for  newly  felled  v/oods  the  following  table  : 


WOOD.  WATER. 


Hornbeam, 

Willow, 

26.0 

it 

Sycamore, 

27.0 

it 

Asb, 

28.7 

it 

Bircb 

30.8 

a 

Oak, 

34.7 

it 

Pedicli  Oak, 

35.4 

it 

White  Fir, 

37.1 

it 

Pine, 

39.7 

a 

Red  Beech, 

39.7 

a 

Alder, 

it 

Asp, 

43.7 

it 

Elm, 

44.5 

it 

Red  Fir, 

45.2 

« 

Lime  Tree 

47.1 

a 

Italian  Poplar, 

48.2 

a 

Larch 

48.6 

a 

White  Poplar, 

a 

Black  Poplar, 

51.8 

ti 

The  amount  of  water  in  wood,  after  one  year’s  dry- 
ing in  the  air,  ranges  from  20  to  25  per  cent.,  and 
when  perfectly  air-dry,  as  it  is  called,  it  still  holds 
from  ten  to  fifteen  per  cent. 

The  specific  weight  of  newly  felled  timber  ranges 
from  0.85  to  1.05  ; that  of  air-dried  timber  from  0.45 
to  0.75.  The  weight  of  one  cubic  foot  of  newly  cut 


140 


SILICIPICATION  OF  WOOD. 


native  timber  would  thus  range  from  fifty  to  sixty- 
five  pounds,  while  that  of  seasoned  wood  would  vary 
from  twenty-eight  to  forty-seven  pounds.  The  total 
expulsion  of  moisture  by  means  of  air-drying,  accord- 
ing to  the  experiments  of  Rumford,  takes  place  only 
at  280°  Fahrenheit.  But  even  if  thus  completely 
dried,  and  then  exposed  again  to  the  atmosphere,  it 
absorbs  nearly  five  per  cent,  of  water  during  the  first 
three  days,  and  continues  to  absorb  until  it  contains 
from  fourteen  to  sixteen  per  cent.,  after  which  it  be- 
comes very  hygroscopic,  losing  or  absorbing  water 
according  to  the  state  of  the  atmosphere. 

The  drying  of  lumber  in  confined  rooms  by  means 
of  hot  air,  or  steam  and  air  alternately,  is  now  largely 
practiced,  and  the  more  on  account  of  the  economy 
of  the  method  than  on  account  of  its  yielding  a supe- 
rior product.  In  some  cases,*  the  wood,  before  being 
exposed  to  artificial  heat,  is  subjected  to  a longitudinal 
pressure,  in  order  to  rupture  the  cells  in  which  the 
moisture  is  confined,  to  the  end  that  it  may  escape 
more  freely  upon  the  application  of  heat.  It  is  claimed 
that  the  wood  is  thus  rendered  more  valuable  for 
nearly  all  the  purposes  for  which  it  is  used,  but  particu- 
larly for  the  hubs,  spokes  and  panels  of  carriages,  etc. 

Pkeserving  Wood. 

The  preservation  of  wood  constitutes  one  of  the 
most  important  questions  with  which  applied  chemis- 
try has  to  deal.  It  has  been  ascertained  by  careful 
statistics  that  the  wooden  structures  alone  on  the 
farms  of  this  country  cost  over  one  hundred  millions 
of  dollars  every  year,  while  the  sleepers  on  the  rail- 


SILICIFIOATION  OF  WOOD. 


U] 

waj^s  cost  twenty-fi\^e  millions  during  the  same  period 
of  time.  If  the  duration  of  all  this  wood  could  be 
doubled,  it  would  save  the  country  twelve  and  a half 
millions  every  year  in  rail-road  ties,  and  fifty  millions 
in  fence  and  farm  buildings.  At  the  same  time,  our 
woodlands  are  being  cut  down  with  fearful  rapidity. 
This  fact  assumes  great  importance,  when  we  reflect 
that  there  exists  a most  intimate  relation  between  the 
climate  of  a country  and  the  extent  of  its  forests. 
This  becomes  at  once  evident,  when  it  is  known  that 
the  springs  of  rivers  do  not  issue  from  subterranean 
reservoirs,  but  consist  chiefly  of  collections  of  atmos- 
pheric precipitates,  rain,  dew  and  snow,  which  have 
percolated  from  higher  levels.  Rainless  regions  are 
always  deficient  in  woodland,  and  there  are  innumera- 
ble instances  where  vast  and  fertile  tracts  of  land 
have  been  changed  into  barren  and  unhealthy  deserts, 
simply  because  they  have  been  stripped  of  their  forests. 
Therefore,  in  lengthening  the  duration  of  wooden  struc- 
tures, we,  at  the  same  time,  prevent  the  destruction 
of  our  forests,  thus  leaving  to  the  coming  generations 
the  same  resources  which  we  have  inherited  from  our 
forefathers. 

The  process  may  be  briefly  described  as  follows : 
The  wood  to  be  treated  is  placed  in  an  iron  chamber, 
which  is  connected  with  a still  containing  coal-tar. 
To  the  latter  heat  is  applied,  until  the  contents  have 
reached  the  temperature  of  600°  Fahr.  The  inventor 
not  only  claims  that  the  thus  impregnated  wood  will 
be  completely  protected  against  the  moisture  of  the 
atmosphere,  but  also  that  it  is  rendered  “ nearly  as 
indestructible  as  granite.”  In  order  to  comprehend 
this  process,  it  is  necessary  that  we  should  examine 

7* 


142 


SILICmCATION  OF  WOOD. 


the  nature  of  the  products  which  are  given  off  in  heat- 
ing coal-tar,  and  the  changes  which  they  produce  on 
entering  the  pores  of  the  woody  fibre.  Coal-tar  con- 
sists, as  is  well  known,  of  a number  of  substances — 
acid,  basic  and  neutral ; of  the  latter,  some  are  liquid, 
some  solid.  In  subjecting  tar  to  distillation,  the  first 
products  given  off  are  ammonia  and  probably  also 
permanent  gases;  then  water  is  evolved,  together 
with  various  ammoniacal  substances,  and  a brownish 
oil  of  a noxious  smell  and  of  less  specific  gravity  than 
water.  The  latter  is  associated  with  the  so-called 
light  oils,  the  portion  in  which  they  are  contained 
being  generally  gathered  separately  in  tar  distille- 
ries. They  amount  to  from  five  to  ten  per  cent.,  and 
when  the  temperature  has  reached  320°  Fahr.,  it  may 
be  concluded  that  they  have  passed  over.  The  oils 
distilling  at  a later  stage  contain  large  quantities  of 
naphthalin  and  paranaphthalin,  both  solid  hydrocar- 
bons, of  which  the  first  appears  at  about  400°  Fahr. 
They  are  often  present  in  such  quantities  that  the 
condensed  distillate  assumes  the  consistency  of  butter. 
Carbolic  or  phenic  acid  is  given  off  a little  earlier,  but 
the  giving  off  of  naphthalized  oils  continues  up  to 
550°  Fahr.,  when  a resinous,  yellowish  product  ap- 
pears, which  can  be  easily  kneaded  between  the  fingers. 
The  remainder  is  the  black,  pitchy  mass,  used  in  the 
construction  of  Nicholson’s  pavement. 

Among  the  various  substances  here  enumerated, 
the  phenic  acid  alone  is  that  to  which  any  preserva- 
tive properties  can  be  ascribed.  It  has  been  deter- 
mined that  tar  from  cannel  coal  contains  seven  per 
cent.,  that  of  Staffordshire  coal  four  and  a half,  and 
tar  from  Newcastle  coal  two  and  a half  per  cent,  of 


SILICIFICATION  OF  WOOD. 


143 


this  acid.  The  average  quantity  of  phenic  acid  in 
coal-tar  would  therefore  be  less  than  five  per  cent.; 
moreover,  it  is  never  found  in  the  free  state,  but 
always  in  combination  with  bases,  whereby  its  effi- 
ciency is  greatly  impaired.  Again,  being  soluble  in 
fresh  and  salt  water,  it  is  easily  and  rapidly  washed 
out,  finally  leaving  the  wood  as  completely  liable  to 
decay,  as  well  as  to  destruction  by  insects,  as  it  was 
before  treatment.  These  facts  are  sufficient  to  justify 
us  in  drawing  the  conclusion  that  the  vapors  of  coal- 
tar  are  not  efficient  preservatives. 

This  fact  was,  indeed,  particularly  reported  upon 
by  the  Dutch  Government  engineers.  They  dis- 
covered that  after  thirteen  months’  exposure,  piles 
which  had  been  creosotized  under  Mr.  Bethel’s  special 
superintendence,  were  found  so  completely  free  from 
the  impregnating  material  that  the  teredo  navalis  had 
eaten  up  and  destroyed  these  to  a thickness  of  one 
inch  and  a'quarter.  Tlie  same  fact  was  also  reported 
by  Mr.  Stevenson,  the  famous  English  engineer,  in 
the  case  of  the  piles  and  wood-work  on  the  Woolwich 
side  of  the  Thames.  The  dead  oil  had  been  completely 
washed  out,  and  the  destruction  of  the  wood  by  decay 
and  by  worms  was  proceeding  at  such  a rate,  that  Mr. 
Stevenson  expected  to  see  the  piles  totally  destroyed 
before  the  expiration  of  three  years  from  the  time 
when  they  had  been  impregnated. 

Again,  for  many  very  important  purposes  this  pro- 
cess is  inapplicable,  on  account  of  the  intolerably 
ofiensive  smell  of  the  dead  oil  and  other  products  of 
the  dry  distillation  of  bituminous  substances. 

In  a pamphlet  before  us,  it  is  stated  that  there  is 
no  record  in  the  books  of  any  thing  like  this  process 


144 


SILICIFIOATION  OF  WOOD. 


having  ever  been  known  to  the  world  prior  to  its  dis- 
covery by  Mr.  L.  S.  Eobbins.  It  is  claimed  to  be  as 
new  as  was  the  sewing-machine  or  the  telegraph. 
We  presume  that  Mr.  Eobbins  did  not  know  of  the 
process  patented  by  Frantz  Moll,  in  England,  in  1835, 
which  is  as  follows  : The  wood  is  placed  in  a close 

cliamber,  which  is  connected  with  one  or  more  stills. 
The  operation  of  impregnating  is  begun  by  heating 
the  inside  of  the  chamber  by  a steam  pipe  to  a tem- 
perature sufficiently  high  to  maintain  the  vapors  con- 
taining the  phenic  acid  in  a vaporized  state.  But  be- 
fore these  are  introduced,  the  watery  vapor  from  the 
damp  timber  is  allowed  to  escape,  after  which  heat  is 
applied  to  the  still  containing  the  light  hydrocarbon 
oils,  or  the  ‘‘  eupion,’*  as  the  mixture  was  named  by 
Moll.  When  it  is  thought  that  the  timber  has  been 
sufficiently  impregnated  witli  these  vapors,  the  surplus 
is  drawn  off,  and  vapors  from  another  still,  containing 
the  heavy  oils,  are  admitted  into  the  chamber.  Fi- 
nally, boiling  liquid  creosote  is  introduced  into  the 
chamber  by  a pipe,  in  a quantity  sufficient  to  cover 
all  the  wood  therein.  It  will  be  seen  that  this  process 
is  substantially  that  of  L.  S.  Eobbins,  but  was  recom- 
mended in  1858  by  Dr.  Krieg,  in  connection  with 
soluble  glass,  for  the  preservation  of  all  wood-work 
against  tire  and  rot. 

Wooden  Eoof  Shingles. 

One  of  the  most  valuable  applications  of  the  solu- 
ble glass  may  be  recommended  for  shingles  and 
wooden  roofs  of  farm-houses  in  the  country,  and 
near  rail-roads,  where  the  sparks  of  the  locomotives 


SILICIFICATION  OF  AVOOP. 


145 


have  frequently  caused  conflagrations  and  destruction 
of  property. 

The  operation  is  quite  simple,  and  the  expense  hut 
trifling;  the  process  has  already  been  described,  but 
it  may  be  still  more  simplified  in  the  following 
manner  : 

After  the  steaming  of  the  shingles  in  boilers  or  in 
tanks,  where  steam  of  300  to  350°  is  led  into  them  for 
several  hours,  they  are  dried  and  thrown  into  a weak 
solution  of  liquid  silica,  standing  about  25°  13.,  from 
which  they  are  taken  out  and  exposed  to  the  air  before 
they  are  quite  dry,  a weak  solution  of  chloride  of  cal- 
cium is  thrown  over  them  or  sprinkled  over  them  with 
a broom  ; when  quite  dry  they  are  fit  for  use.  They 
will  not  burn  nor  be  lighted  by  the  sparks  if  exposed 
to  a direct  fire — will  not  light  in  a surrounding  fire. 
An  intense  heat  of  long  duration  may  char  them  on 
the  surface  ; they  are,  however,  quite  safe  against  any 
infiammation. 

Street  Pavements. 

As  a rule,  competent  engineers  express  doubts  as  to 
the  merits  of  the  Nicholson,  and  of  wooden  pavements 
of  all  patterns. 

In  the  Nicholson  structure  the  road-bed  is  of  sharp, 
clean  sand,  of  the  proper  thickness.  A basis  is  then 
made  by  laying  common  boards,  dipped  in  hot  coal- 
tar,  lengthwise  on  stringers  of  like  material  laid  from 
curb  to  curb.  The  blocks  forming  the  superstructure 
are  of  Southern  hard  pine,  three  by  four,  and  are  set 
on  end  in  rows,  crosswise  of  the  street — the  blocks 
before  setting  being  dipped  to  half  their  length  in  a 


146 


SILTCIFICATION  OF  WOOD. 


bath  of  coal-tar.  Between  the  rows  of  blocks  inter- 
vene pickets  of  thin  board  set  on  edge,  and  leaving  an 
opening  between  the  rows  of  blocks  of  an  inch  or 
nearly  in  depth.  This  opening  is  filled  with  clean 
screened  gravel,  rammed  down  with  a paver’s  ham- 
mer, and  an  iron  blade  made  for  the  purpose,  and  the 
surface  is  covered  with  hot  coal-tar.  The  gutter  ex- 
hibits its  lowest  point  half  a foot  from  the  curb.  The 
whole  surface  is  covered  with  coal-tar  sufiiciently 
boiled  to.be  tough  and  fibrous,  but  not  brittle,  upon 
which  is  sprinkled  a layer  of  fine  gravel  and  conimon 
sand.  The  Stafford  pavement  differs  from  the  J^ichol- 
son,  in  the  laying  of  large  blocks  prepared  after  the 
Seely  patent,  resting  upon  stringers,  which  in  their 
turn  may  be  supported  by  any  specified  road-bed. 
Provided  the  road-bed  is  sufficiently  secure,  say  of 
strong  concrete,  and  the  upper  deposit  is  made  suffi- 
ciently complete,  the  Stafford  pavement  cannot  but 
compare  favorably  with  other  wooden  pavements, 
and,  for  simplicity,  is  quite  superior  to  the  Nicholson. 
The  Stafford  pavement  appears,  at  the  present  mo- 
ment, to  be  the  favorite  one  in  the  City  of  New- York, 
as  a large  contract  is  now  carried  out  for  the  upper 
part  of  the  city. 

Both  obviate  certain  objections  in  surface  way 
which  pertain  to  the  Belgian,  in  the  wear  and  tear  of 
vehicles  and  horses,  and  the  noise  or  reverberation  of 
wheels ; but  both  are  inferior  to  the  asphaltic  road  in 
these  respects,  while  the  asphaltic  has  one  great 
superiority  valuable  as  preventive  of  accident,  to  wit, 
the  beating  of  the  hoof  of  the  horse  is  rendered  very 
audible — audible  above  all  other  sounds — so  as  to  be 
measurable  by  the  ear  in  the  matter  of  distance.  This 


SILICIFICATIOW  OF  WOOD. 


147 


latter  advantage  can  only  be  estimated  by  persons 
who  have  taken  occasion  to  note  the  extent  to  which 
one  fails  into  the  habit  of  measuring  the  distance  of  a 
vehicle  from  any  given  crossing,  by  the  ear;  and  one 
of  the  main  liabilities  to  accident,  occurring  from 
wooden  pavements,  is  the  muffling  or  comparative 
muffling  of  the  hoof  beat.  In  this  respect,  in  fact,  any 
form  of  concrete  pavement  possesses  material  advanta- 
ges over  either  the  stone  block,  which  exaggerates  the 
rumble  of  wheels  and  obscures  the  hoof-beat,  or  the 
wooden  pavement,  which  reduces  both  in  about  equal 
proportions.  In  a word,  a grave  objection  to  the 
Kicholson  pavement  is  the  fact,  tliat  in  just  one  respect 
it  is  a trifle  too  noiseless  for  the  safety  of  pedestrians 
in  crossing,  especially  iii  these  days  when  every  driver 
seems  to  be  possessed  with  the  devil  to  run  over  some 
body.  Again,  in  case  of  extensive  conflagration  in 
any  part  of  the  city,  the  wooden  pavement  might 
prove  a dangerous  ally  by  ignition,  an  instance  of 
which  has  recently  occurred  in  Philadelphia.  Neither 
of  the  wooden  pavements  above  named  command  the 
unqualified  admiration  of  practical  engineers  as  yet, 
though  the  test  of  use  is  the  measure  of  merit  in  these  . 
matters,  and  neither  has  been  in  use  here  sufficiently 
long  to  warrant  the  expression  of  an  opinion. 

The  Parisian  system  has,  since  1854,  manifested 
strong  preference  for  the  asphalt  road  upon  the  con- 
crete foundation.  In  1854,  nine  hundred  and  sixty 
square  yards  of  asphalt  road  were  laid  in  Paris,  and 
since  then  the  use  of  the  material  has  steadily  in- 
creased, until  at  present  it  is  ranked  as  well  adapted 
for  purposes  of  heavy  traffic  on  the  most  frequented 
thoroughfares.  Up  to  1866,  96,000  square  yards  had 


148 


SILICIFICATION  OF  WOOD, 


been  put  down ; in  1867  the  surface  added  was  54,000 
in  Paris  proper,  and  84,000  in  all  in  the  department 
of  the  Seine,  making  a total  in  thirteen  years  of 
180,000  square  yards.  The  contract  of  the  Cie  Gene- 
rale  des  Asphaltes  with  the  City  of  Paris,  covered  at 
that  date  at  least  96,000  square  yards  more,  to  be  put 
down  in  1868  and  1869.  The  ancient  streets  of  Paris 
were  without  sidewalks,  and  were  paved  with  large 
square  blocks,  with  grades  sloping  from  the  sides  to 
the  middle,  forming  a gutter  on  the  central  line. 
Sidewalks  began  to  appear  in  1825,  and  in  the  same 
year  the  reversal  of  the  surface,  bringing  the  gutter 
to  the  sides,  was  introduced.  In  1852  the  system  of 
MacAdam  was  applied  to  the  old  boulevards,  and  in 
1858  this  method  was  improved  for  heavy  traffic  by 
introducing  margins  along  the  sides,  from  two  to  four 
yards  in  width,  paved  with  small  blocks  of  Belgian 
porphyry — the  germ  of  the  sidewalk  as  now  used. 

The  first  cost  of  asphalt  streets  is  greater  than  that 
of  Macadamized,  while  the  cost  of  repairs  is  considera- 
bly less  ; and,  again,  the  first  cost  of  the  asphalt  is 
less  than  that  of  the  Belgian  pavement,  while  the  ex- 
pense of  repairing  is  greater.  The  asphalt  coating, 
one-sixth  of  a foot  thick,  is  supported  upon  a road-bed 
of  concrete,  composed  of  ninety  parts  gravel  to  forty 
parts  of  mortar,  about  a quarter  of  a foot  in  thickness, 
and  resting  upon  the  compacted  soil  bed  beneath.  Pro- 
vided the  requisites  of  thorough  surface  and  under 
drainage  have  been  observed,  the  asphalt  roofing, 
being  utterly  impervious  to  water,  the  road-bed  of 
concrete  waxes  harder  and  drier  with  age,  and,  once 
made,  is  imperishable.  Pepairs  are  easy,  and  consist 
simply  in  cutting  away  the  damaged  roofing  of  asphalt 


SILICIFICATION  OF  WOOD. 


149 


and  replacing  it  with  new.  As  compared  with  the 
Belgian  pavement,  the  liability  to  fall  of  horses  being 
driven  over  the  asphaltic  road  is  1 in  1,409  to  1 in 
1,308  on  the  former,  proving  the  superiority  of  the 
asphaltic  surface  in  this  respect — that  is,  in  surety  of 
foothold. 

The  merits  of  the  wooden  pavement  are  its  noise- 
lessness, its  reduction  of  the  mortality  of  horses,  its 
reduction  of  the  wear  and  tear  of  vehicles,  and  its 
effecting  a utilization  of  the  utmost  per  centage  of 
draught  force,  and  these  are  all  merits  to  an  equal  de- 
gree of  the  asphaltic  road,  and  may  be  made  merits  of 
any  concrete  whatsoever.  The  increased  mortality  in 
horses  occasioned  by  the  Buss  and  Belgian  and.  other 
stone  pavements  in  this  city,  is  estimated  at  3,500 
annually — an  item  of  considerable  importance  in  the 
discrimination  between  pavements  for  thoroughfares. 
As  between  the  two  typical  structures,  the  Belgian 
and  the  Nicholson,  from  data  already  supplied,  it  may 
be  estimated  that,  with  the  attrition  of  Broadway,  the 
former  would  last  fifteen  years  against  a last  of  half 
that  period  in  the  case  of  the  latter,  if,  indeed,  the 
Nicholson  can  be  regarded  as  equal  to  the  necessities 
of  Broadway  at  all.  It  is  seen,  therefore,  that  while 
the  stone  block  (Belgian  or  Buss)  is  open  to  grave  ob- 
jections on  the  one  hand,  the  wooden  pavements 
(Nicholson  and  Stafford)  are  open  to  equally  serious 
objections  on  the  other  hand,  on  the  score  of  lessened 
durabilit}^  The  concrete  pavement — the  value  of 
which  has  been  happily  settled  in  Paris — effects  a 
^ union  of  the  better  qualities  of  both,  without  the  ob- 
jections appertaining  to  either  ; and,  as  the  minds  of 
engineers  and  inventors  are  already  beginning  to  turn 


150 


SILICIFIOATION  OF  WOOD. 


in  this  direction,  notliing  is  hazarded  in  predicting 
that  the  ideal  or  coming  pavement  will  be  developed 
from  the  present  crude  concretes.  The  asphalt  road, 
one  triumph  of  concretion,  the  heton  Coignet^  another 
triumph  in  a direction  of  equal  practical  importance, 
the  attempts  at  concrete  from  inexpensive  material 
in  this  country,  all  point  to  the  hypothesis  that  the 
solution  of  the  long  mooted  pavement  problem  is  at 
hand,  in  the  evolution  of  a concrete  roadway  com- 
bining the  durability  of  the  stone-block  with  the  ad- 
vantages of  the  wooden  superstructure.  Valuable 
hints  as  to  the  constitution  of  concretes  may  be  found 
in  the  reports  of  Messrs.  Beckwith  on  heton  Coignet^ 
and  asphalt  and  bitumen  as  applied  to  the  construc- 
tion of  streets  and  sidewalks  in  Paris;  and,  in  the 
way  of  American  invention,  the  constitution  of  the 
Fiske  concrete  pavement,  under  the  Hairm  Burlew 
patent,  may  be  studied,  but  has  proved  so  far  a great 
failure  in  Fifth  Avenue,  where  the  concrete  had  to  be 
taken  up  again  last  winter.  This  pavement  is  com- 
posed of  gravel,  broken  stone,  cinders  and  coal  ashes, 
(free  from  all  foreign  substances,)  mixed  in  definite 
proportions  with  tar,  rosin  and  asphaltum.  The  road- 
bed properly  prepared,  the  composition  is  spread  on 
in  layers  of  moderate  thickness,  successively  rolled 
with  heavy  rollers  for  uniformity  and  compactness. 
These  layers  form  a sufiiciently  strong  roadway  of 
from  half  to  three-quarters  of  a foot  in  depth,  and  can 
be  put  down  at  an  expense,  per  square  foot,  not  ex- 
ceeding the  expense  of  the  asphalt  road  as  constructed 
in  Paris.  It  remains  for  years  and  attrition  to  test 
the  practical  value  of  this  concrete;  but,  in  general, 
it  may  be  remarked,  that  it  is  heartily  and  highly 


SILICIFICATION  OF  WOOD. 


151 


commended  bj  thonghtfiil  engineers  as  a step  in  the 
right  direction.  The  sonorousness  of  the  hoof-beat,  as 
enabling  the  pedestrian  to  measure  tlie  imminence  of 
passing  vehicles,  is  an  element  of  concretes  over 
wooden  pavements,  illustrated  in  an  eminent  degree 
bj  the  asplialtic  road,  the  value  of  which,  as  a preven- 
tive of  accidents,  cannot  be  over-estimated.  A pave- 
ment may  be  too  noiseless  as  well  as  too  noisy  for 
immunity  in  this  respect,  and  by  all  means  let  the 
capacity  of  the  concrete  be  developed  to  the  utmost. 
The  Commissioners  of  the  Park  have  also  developed 
some  excellent  roadways  in  their  admirable  system  of 
earth  roads  upon  a similar  principle  ; though  in  rela- 
tion to  the  Park,  the  problem  has  been  less  difficult 
of  solution,  no  necessity  existing  to  provide  for  the 
contingency  of  heavy  traffic.  In  its  capacity  for  the 
combination  of  all  the  qualities  which  experience  has 
proved  to  be  desirable  in  a roadway  for  large  cities, 
the  concrete  must,  therefore,  be  ranked  as  superior  to 
either  of  its  competitors,  with  some  most  important 
and  indispensable  improvements  to  be  applied,  and  as 
embodying  in  itself  the  germ  of  the  coming  pavement 
in  this  city  ; and  the  suggested  reforms  in  the  sewerage 
system  having  been  carried  out,  attention  may  be  di- 
rected to  the  production  of  an  inex])ensive  concrete, 
analogous  to  the  asphaltic  road. 

Various  Systems  Adopted  for  Poadway 
Pavemi:nts. 

A great  variety  of  systems  have  been  adopted  for 
roadway  pavements.  The  most  convenient  classifi- 
cation of  them  is  into  gravel  compositions,  broken 


152 


SILICIFIOATION  OF  WOOD. 


stone,  plank,  wooden  block,  cobble  stone  or  pebble 
stone  block  and  iron  block  pavements  and  tramways. 
The  first  attempts  at  pavements  generally  commence 
with  the  use  of  gravel.  Roads  thus  made  possess  the 
advantages  of  cheapness  of  material  and  construction. 
In  tlie  Central  Park,  where  there  are  probably  the 
most  perfect  roads  in  this  country,  they  have  shown 
better  endurance  than  those  made  on  the  MacAdam 
plan.  Gravel  roads,  when  properly  constructed  and 
maintained,  are  comparatively  smooth  and  noiseless, 
besides  affording  excellent  foothold  for  horses.  The 
great  objections  to  them  are  that  they  cannot  be  kept 
firm  enough  to  afford  easy  draught  for  heavy  traffic ; 
that  they  lack,  in  a high  degree,  permanence,  and  are 
constantly  requiring  repairs  ; that  they  are  difficult  to 
keep  clean  and  to  drain  properly ; the  rapidly  grind- 
ing and  crushing  to  powder  tending  greatly  to  cause 
dust  in  dry  weather  and  mud  in  wet  weather  ; and, 
lastly,  that  the  best  construction  yet  attained  has 
failed  to  prevent  them  from  washing* into  gullies. 
Under  the  head  of  second  composition  pavements, 
may  properly  be  included  pavements  formed  by  the 
combinations  of  several  materials,  such  as  the  famous 
asphalt  pavement  of  Paris,  concrete,  heton^  gutta 
percha,  slag,  cinder,  and  other  pavements  ; also,  those 
formed  according  to  the  experiments  of  McUeil,  partly 
of  broken  stone  and  partly  of  pieces  of  cast  metal,  laid 
on  a sub-pavement  of  rubble  stone.  The  asphalt  pave- 
ment of  Paris,  so  often  recommended  in  newspaper 
articles,  is  really  quite  an  imperfect  pavement.  It  is 
generally  formed  on  a foundation  of  MacAdamized 
road.  Powdered  asphalt  is  placed  on  the  foundation, 
and  stamped  with  hot  rammers  until  it  is  very  hard. 


SILICIFICATION  OF  WOOD. 


153 


and  has  a thickness  of  one  or  two  inches.  It  is  very 
pleasant  and  smooth  to  ride  over,  but  requires  most 
constant  watching  and  repairing.  It  is  slippery  in 
wet  weather,  and  excessively  so  at  a freezing  tem- 
perature. 


Pavements  of  Granite. 

Granite  blocks,  considered  in  every  respect,  form 
one  of  the  most  perfect  pavements  known.  They  are 
preferred,  and  almost  exclusively  adopted  in  London. 
The  Puss  pavement,  the  nearest  approach  to  a perfect 
pavement  yet  constructed  in  this  citjq  has,  in  imitation 
of  the  Poman  pavement,'  a hHon  foundation  of  six 
inches  thick.  The  heton  is  composed  of  one  part 
cement,  to  two  and  a half  parts  of  broken  stone,  and 
two  parts  of  gravel.  On  this  foundation  are  laid  hard 
granite  blocks  ten  inches  deep,  ten  to  eighteen  inches 
long,  and  from  five  to  twelve  inches  wide.  It  is  very 
durable,  and  yet,  as  shown  in  Broadway,  this  excellent 
pavement  has  most  signally  failed,  the  surface  of  the 
granite  used  polishing  and  afi*ording  dangerous  foot- 
hold. What  is  required,  and  this  would  give  a perfect 
pavement,  is  the  adoption  of  the  kind  of  stone  blocks 
used  in  London,  which  do  not  polish  by  wear,  and 
present  joints  about  every  four  inches.  Another 
pavement  is  now  being  substituted  here  in  an  imper- 
fect manner.  The  blocks  now  used  are  of  a coarser 
granite,  twelve  inches  long,  nine  inches  deep,  and  four 
inches  wide,  the  courses  running  at  right  angles  with 
the  line  of  the  street.  What  is  known  as  the  Belgian 
pavement  was,  until  recently,  the  principal  one  in  use 
in  the  old  streets  of  Paris,  and,  as  is  well  known,  has 


154 


SILICmCATION  OF  WOOD. 


been  quite  extensively  adopted  in  this  city.  This 
pavement  has  the  advantage  of  cheapness,  and,  if  well 
laid,  of  economy,  tlie  necessary  and  actual  cost  being 
a little  over  one-half  that  of  the  Nicliolson  pavement. 
The  final  trouble,  however,  is  their  becoming  polished 
and  slippery,  and  hence  they  should  not  be  laid  in 
streets  where  they  are  subject  to  constant  use. 

Iron  Block  Pavements. 

Several  attempts  have  been  made,  with  more  or 
less  success,  to  cast  iron  in  blocks  suitable  for  pave- 
ments. The  chief  objection  is  the  cost  of  iron  ; but 
if  properly  laid,  there  can  be  no  doubt  of  its  being 
cheaper  in  the  end  than  most  other  pavements.  It 
has  failed  here  on  account  of  its  inadequate  and  de- 
fective foundation,  and  on  account  of  the  principle 
employed  of  keying.  The  rings  pressing  on  the  sand 
foundation  gave  too  little  bearing  surface,  and  any 
weight  tended  greatly  to  displace  ol*  overturn  the 
block,  which  occurring,  all  the  neighboring  ones  key- 
ing into  it  were  released,  and  unless  quickly  repaired, 
the  ruin  of  the  whole  pavement  soon  followed.  It 
has  stood  much  better  in  Boston,  and  for  the  simple 
reason  of  its  being  better  laid  It  has  stood  there 
admirably,  and  shows  no  material  signs  of  surface 
wear  after  ten  or  twelve  years  of  constant  use.  It 
can  be  cast  in  such  form  as  to  give  the  best  foothold 
for  horses  drawing  heavy  loads.  It  can  be  kept  per- 
fectly even  and  made  smooth  as  the  Nicholson  pave- 
ment, and  by  its  extreme  hardness  will  give  much  less 
resistance  to  wheels.  Being  of  uniform  quality,  all 
parts  will  wear  equally,  and  as  perfect  a face  will 


SiLICmCATION  OF  WOOD. 


155 


always  be  presented  as  when  new.  Its  smoothness 
tends  greatly  to  lessen  the  noise,  as  this  nuisance  is 
caused  principally  by  the  boxes  of  the  wheels  striking 
against  the  collars  on  the  axle,  and  of  course  increases 
with  roughness  of  pavement  surface.  Iron,  further- 
more,  loses  but  little  from  oxydation.  It  can  be  kept 
as  clean  as  the  Nicholson  pavement,  with  the  advan- 
tage of  non-absorption.  It  has  one  great  advantage, 
in  being  made  so  as  to  be  easily  and  readily  removed 
and  replaced,  the  blocks  formed  from  the  same  pattern 
being  exact  counterparts. 

The  Fiske  Concrete  Pavement. 

This  pavement  is  composed  of  seventy  per  cent,  in 
bulk  of  broken  stone,  coal  or  gravel,  clean  coal  or 
iron  cinders,  not  over  three  inches  in  any  dimensions. 
These  are  passed  over  a screen  with  meshes  one  quar- 
ter inch  square.  The  coarser  portion  is  then  coated 
by  mixing  with  tar,  warm  or  cold,  and  then  spread 
on  the  road-bed  and  heavily  rolled  until  a depth  of 
four  inches  is  attained.  The  finer  portion  is  then 
mixed  with  clean  sharp  sand,  warmed,  and  then 
thoroughly  mixed  wdth  tar,  to  which  has  been  added 
rosin,  carbojapanis  or  pitch.  This  is  placed  on  the 
first  layer  of  coarse  material,  and  rolled  until  a depth 
of  two  inches  is  attained ; after  which  the  surface  is 
covered  with  an  excess  of  clean  sharp  sand,  and  again 
rolled. 


Toe  Nicholson  Pavement. 

We  now  come  to  the  subject  of  wooden  pavements. 
The  first  general  attempt  to  use  wmoden  blocks  for 


156 


SILICIFICATION  OF  WOOD. 


pavements  took  place  some  thirty  years  ago,  both  in 
this  country  and  Europe.  They  are  generally  made 
in  the  form  of  hexagonal  prisms  of  hard  wood,  laid 
directly  on  sand  or  earth.  Leading  off  in  the  list  of 
wooden  pavements  adopted  in  this  city  is  the  Nicholson 
pavement.  In  laying  this  pavement,  the  street  is 
first  prepared  by  a sufficient  covering  of  sand,  which 
is  brought  to  the  proper  crown  with  a straight  edge 
made  fur  that  purpose.  This  surface  is  then  covered 
with  common  round  inch  boards,  laid  lengthwise 
with  the  line  of  the  street.  The  ends  of  these  boards 
rest  on  stringers  of  the  same  material  laid  from  curb 
to  curb. 

Both  sides  of  these  boards  are  covered  with  hot  coal- 
tar.  The  blocks  are  of  Southern  pine,  three  inches 
wide  and  six  inches  deep,  and  are  set  on  end  in  rows 
crosswise  of  the  street.  Before  setting,  the  blocks  are 
dipped  to  half  their  height  in  hot  coal-tar.  Between 
each  row  of  blocks,  and  at  their  base,  pickets  one  inch 
thick  and  three  inches  wide  are  nailed  on  edge.  The 
opening  thus  formed  between  the  rows  is  filled  with 
clean  screened  gravel,  rammed  with  a paver’s  ram- 
mer, an  iron  blade  made  for  that  purpose,  and  then 
covered  with  hot  coal-tar.  The  whole  of  the  upper 
surface  of  the  pavement,  when  laid,  is  covered  with 
hot  coal-tar,  boiled  to  a consistency  which,  when  cold, 
is  to  be  tough,  fibrous  and  not  brittle,  and  then  cov- 
ered with  fine  gravel  and  common  sand.  After  the 
top  gravel  has  become  packed  on  the  surface  and  in 
the  grooves,  the  street  is  swept. 


SILICIFIOATION  OF  WOOD. 


157 


The  M’Gonegal  Pavement. 

This  pavement,  claimed  to  be  an  improvement  on 
the  Nicholson,  to  which  it  is  similar,  consists  of  a 
foundation  of  two  inches  of  on  which  are  placed 

wooden  blocks  six  inches  deep,  two  and  three-quarter 
inches  wide,  and  from  four  to  sixteen  inches  in  length. 
Holes  of  one  and  a half  inches  in  diameter,  and  three 
and  a half  inches  deep,  are  bored  in  each  block,  and 
then  triangular  grooves  formed  on  each  side  of  the 
blocks,  so  that  when  two  blocks  are  placed  together, 
there  will  be  a square  opening  one  and  a quarter  inch 
square  to  receive  a wooden  dowel  or  key.  The  wood 
used  for  blocks  and  keys  is  prepared  for  preservation 
by  Pobbins’  process.  In  laying,  the  blocks  and  kej^s 
are  dij)ped  in  hot  coal-tar.  The  perforations  in  the 
blocks  are  filled  with  clean  roofing  sand.  The  pave- 
ment is  finished  by  a coating  three-quarters  of  an  inch 
in  thickness  of  coal-tar  and  fine  sand.  These  are  the 
specifications  as  we  have  described  them  ; but  where 
this  pavement  has  been  laid  in  this  city,  a foundation 
of  fiooring  of  tarred  boards  has  been  substituted  for 
that  of  heton. 

The  Stowe  Pavement. 

In  constructing  this  pavement,  which  is  also 
wooden,  and  a cheap  form  of  the  Nicholson,  the  street 
is  first  filled  with  sand,  loam  or  loose  earth,  free  from 
stones,  to  within  about  six  inches  of  the  desired 
street  grade,  but  smoothed  ofi*  so  as  to  conform  to 
the  desired  arch  or  crown  of  the  street;  then  blocks 
' of  sound  pine  or  spruce  wood  three  inches  in  thick- 

8 


158 


SILICIFICATION  OF  WOOH. 


nessj  and  six  inches  in  length,  are  set  on  their  ends  in 
a tier  across  the  street,  these  blocks  being  cut  square 
at  both  ends.  A tier  of  blocks  made  wedge-shape  at 
their  ends  by  beveling  on  one  side  is  set  across  the 
street  close  against  the  first  tier  of  square-ended  blocks, 
which  are  set  up  as  before,  and  so  on  alternate  tiers 
of  square  and  wedge-shaped  blocks  are  placed,  until  a 
space  of  ten  feet  or  more  is  covered,  then  the  wedge- 
shaped  blocks  are  driven  down  into  the  sand  or  earth 
wn'tli  rammer  and  swage  until  the  foundation  is  of  the 
required  compactness.  The  cells  or  spaces  between 
the  three-inch  blocks  are  filled  with  clean  coarse  gravel, 
not  exceeding  three-fourths  of  an  inch  in  diameter, 
thoroughly  driven  with  rammer  and  swage,  then  the 
gravel  saturated  with  hot  coal-tar,  and  the  whole 
surface  covered  with  hot  coal-tar,  and  lastly,  the  pave- 
ment covered  with  fine  gravel  or  sand. 

The  Ekown  and  Miller  Patemeet. 

This  pavement  is  also  similar  to  the  Nicholson,  only 
that  its  blocks  are  not  set  vertically,  but  at  an  angle 
of  forty-five  degrees,  and  rest  on  sills  of  a prismatic 
form,  which,  in  turn,  rest  on  boards  placed  five  feet 
apart,  and  parallel  with  the  line  of  the  street. 

The  Pobbins’  Payement. 

This  is  another  of  the  multifarious  wooden  pave- 
ments recently  introduced  in  this  city.  It  is  very 
similar  to  the  Nicholson,  only  the  woqd  used  is 
first  prepared  by  Pobbins’  patent  wood  preserving 
process. 


SlLtClB'lCATlON  OE'  WOOD. 


159 


The  Stafford  Pavement 

is  only  another  imitation  of  the  great  original  Nichol- 
son. The  blocks  are  dressed  to  a imiform  thicknessj 
grooved  in  the  middle  with  a double  dovetail,  two 
and  one-half  by  three-fourth  inches,  each  side  of  the 
block  beveled  at  one  end,  and  running  to  an  edge  so 
as  to  form  a groove  on  the  upper  surface. 

Seeley’s  Concrete  Pavement, 

now  being  put  down  in  Eleventh-street,  near  IJniver^ 
sity  Place,  consists  of  sulphur,  three  parts;  gas  tar, 
twelve  parts  ; silica  (pebbles)  sixty  parts,  by  weight. 
The  pebbles  are  heated  230®  Fahrenheit  before  being 
mixed  with  the  melted  sulphur  and  tar. 

General  Directions  for  the  Application  of  Silicate 
OF  Soda  to  Wooden  Pavements  and  Cements. 

The  following  method  of  application  of  the  silicate 
is  recommended  by  the  author,  and  is  reliable ; 

The  planks  and  wooden  blocks,  intended  as  pave- 
ment, the  si^e  of  the  planks  being  from  10  to  12  feet 
in  length  and  1 inch  in  tliickness,  and  the  blocks 
from  10  to  12  inches  square,  and  in  the  first  place  ex- 
posed the  iron  boilers  to  a temperature  of  300®  F.  for 
several  hours,  or  kept  for  4-6  hours  in  boiling  water, 
containing  2 per  cent,  of  soda  ash,  which  possesses  the 
property  of  dissolving  the  albumen  and  sap  contained 
in  the  cells  of  the  wood,  and  by  the  boiling  the  color- 
ing matter  is  extracted  from  the  wood  ; when  taken 


160 


SlLIcmCATION  OF  WOOD. 


from  the  boilers,  they  are  brought  in  drying  chambers 
of  high  temperature,  and  then  removed  to  vats  con- 
taining crude  carbolic  acid  and  tar  water,  standing 
for  6-8°  B.,  which  will  enter  into  the  pores,  left  open 
by  the  previous  process,  and  a large  portion  of  the 
liquid  will  be  absorbed  ; from  thence  they  are  thrown 
into  vats  containing  hot  silicate  of  soda,  standing  20^ 
B.,  and  left  therein  for  4-6  hours  ; they  are  then  re- 
moved and  dried  either  in  air  or  hot  chambers.  When 
perfectly  dry  they  are  suitable  for  being  put  on  a 
smooth  ground,  which  may  consist  of  a cement  ofsili- 
cated  hydraulic  lime  or  cement. 

If  strong  cements,  or  lutes,  where  various  other  sub- 
stances along  with  the  dry  silicate  and  metallic  oxides 
are  to  be  employed,  the  soluble  glass  is  not  diluted,  but 
employed  from  30-35°  B.,  sufficiently  to  make  a 
plastic  composition  ; but  where  it  is  intended  for 
mending  or  tilling  cracks  or  holes,  either  in  stoves  or 
iron  castings,  discretion  of  the  consistency  of  the  mass 
must  be  used,  as  it  may  be  more  advantageous  for  the 
cement  to  dry  slowly,  so  as  to  prevent  too  sudden  a 
contraction. 

Bor  painting  or  coating  on  stone,  it  is  useful  to 
apply  the  dilute  by  a syringe,  and  if  necessary,  repeat 
the  operation  2-3  times  after  each  drying.  For  pre- 
serving monuments,  tombstones,  marble  columns,  etc., 
the  dilute  silicate  of  soda  may  be  used  as  a wash,  with 
or  without  the  addition  of  baryta,  (the  precipitated 
sulphate  of  baryta  is  always  preferred,  although  ex- 
pensive,) lead,  zinc  or  limewash,  by  means  of  a paint 
brush,  and  according  to  the  condition  of  the  stone  as 
to  porosity.  If  the  chloride  of  calcium,  chloride  of 
iron,  or  dilute  hydrofluoric  acid  are  applied  upon  the 


SILICIFICATION  OF  WOOD. 


161 


surface  of  the  stoue,  cement  or  paint,  they  are  thrown 
over  the  silicated  surface  uniformly,  so  as  to  cover 
every  part  of  the  material  to  be  treated.  In  all  cases 
it  is  understood  that  the  silicate  application  is  to  be 
applied  on  new  stone,  for  it  will  not  adhere  on  old 
paint ; therefore,  if  it  is  to  be  used,  it  is  indispensable 
that  it  be  first  removed  by  soap,  caustic  alkali,  spirits 
of  turpentine,  or  even  acids,  and  when  perfectly  clean 
and  dry,  the  operation  of  silicating  may  take  place. 
In  all  cases  wliere  the  substances  are  to  be  painted  or 
undergo  a silicification,  it  may  be  repeated  2-3  times, 
at  each  interval  of  at  least  12  hours  ; a weak  hydro- 
fluoric acid  may  in  all  cases  be  used  as  a wash  over 
the  silicated  stones  ; 1,000  square  feet  of  wall  covering 
can  be  executed  with  200  gallons  of  dilute  silicate  of 
either  soda  or  potash.  In  diluting  the  silicate,  it  is 
well  to  employ  3 applications  of  various  qualities,  such 
as,  for  instance,  the  first  coat  may  consist  of  1 part  of 
silica  to  2 parts  of  water,  and  another  of  equal  quan- 
tities of  water,  and  the  last  coat  the  dilution  to  be  1 
part  of  water. 

For  Preservation  of  Walls. 

It  is  well  known  that  brick  absorbs  its  weight  of 
moisture  and  requires  much  attention.  Tlie  external 
surfaces  of  the  walls  to  be  protected  are  first  washed 
with  a silicate  of  soda,  which  is  applied  again  and 
again,  until  the  bricks  are  saturated,  and  the  silicate 
ceases  to  be  absorbed.  The  strength  of  the  solution  is 
regulated  by  the  character  of  tlie  bricks  upon  which 
it  is  to  be  applied,  a heavier  mixture  being  used  upon 
porous  walls,  and  a lighter  one  on  those  of  denser 


162 


SILICIFICATION  OF  WOOD. 


texture.  After  the  silicate  has  become  thorouo-hlv  ab- 

O €/ 

sorbed,  and  none  is  visible  upon  the  surface,  a solution 
of  chloride  of  calcium  is  applied,  which,  immediately 
combining  with  the  silicate  of  soda,  forms  a perfectly 
insoluble  compound,  which  completely  tills  up  all  the 
interstices  in  the  brick  or  stone,  without  in  any  way 
altering  its  original  appearance.  By  this  operation 
the  wall  is  rendered  perfectly  water-tight,  and,  as  the 
pores  of  the  bricks  are  thoroughly  filled  for  a consider- 
able depth  from  the  surface  with  the  insoluble  com- 
pound, which  is  entirely  unafiected  by  atmospheric 
infiuences,  no  subsequent  process  is  necessary. 

The  Protection  of  Bail-Koad  Sleepers,  Cross- 
Ties,  Frame  Houses,  Telegraph  Poles,  Timber, 
Staves,  Shingles,  Laths,  Tanks,  Tubs,  Casks, 
Barrels,  (Petroleum,  Naphtha,  Spirits  Turpen- 
tine, Alcohol,  Linseed  Oil,)  Cisterns,  and  Every 
Description  of  Wood,  against  Fire,  Dry  Pot 
AND  Leakage. 

The  seasoning  or  initiatory  preparation  of  the  lum- 
ber, so  as  to  destroy  the  organic  or  nitrogenized  mat- 
ters enclosed  in  all  the  cells  of  vegetable  matters,  are 
dissolved  and  washed  out  of  it ; or,  in  other  words, 
the  removal  of  all  the  albumen,  sap  and  coloring  mat- 
ter, is  effected  by  exposing  from  four  to  six  hours  to 
boiling  water,  containing  about  one  per  cent,  of  soda 
ash  in  solution.  They  are  then  withdrawn  and  dried 
in  hot  rooms,  and  then  thrown  into  tanks  containing 
the  tar  and  carbolic  acid  water,  and  left  for  a few 
hours,  then  dried  again  and  thrown  into  a hot  solu- 
tion of  silicate  of  soda,  standing  20°  B.,  in  which  they 


SILICTFICATION  OF  WOOD. 


163 


are  left  for  ten  or  twelve  hours.  When  removed  from 
here  a weak  liinewash  is  applied  with  a brush  or 
sponge,  consisting  of  10  lbs.  slaked  lime  to  40  gallons 
of  water,  when  likewise  thej^  are  removed  to  a dry  or 
hot  air  ; after  that  a weak  wash  of  chloride  of  calcium 
is  thrown  or  brushed  over  them  when  nearly  dry. 
Tlie  process  is  then  finished,  and  the  articles  so  pre- 
pared will  resist  the  elements  as  above  stated.  They 
increase  in  weight  by  this  process  about  6 perioent. 
After  this  treatment,  they  assume  upon  the  first  dry- 
ing a glazed  appearance,  and  the  pores  are  filled  with 
insoluble  silicas  precipitated  by  the  action  of  the  tar 
licjuor  upon  the  alkali  of  the  silicate  of  soda.  Barrels 
which  have  been  treated  may  be  rendered  perfectly 
impervious,  by  filling  up  the  chimes  (the  inside  of  those 
barrels  having  been  treated  with  the  silicate  of  soda 
and  chloride  of  calcium)  with  a thin  silicated  cement 
applied  on  the  interstices.  'No  air  nor  any  liquid  will 
then  have  any  effect ; the  lightest  liquid  maj^  then  be 
kept  in  those  prepared  barrels  without  escaping ; fiour, 
butter,  lard,  and  many  other  perishable  substances  may 
be  kept  fur  a length  of  time  in  barrels  so  prepared. 
Spirits  of  turpentine,  linseed  oil,  alcohol,  and  other 
spirituous  liquors,  may  safely  be  transported  and  kept 
for  a length  of  time,  without  evaporation  or  loss  in  the 
contents  of  the  barrels.  Telegraph  poles^  which  are 
from  twenty  to  thirty  feet  long,  require  a different 
treatment  for  their  seasoning  before  they  undergo  the 
silicification.  They  are  steeped  first  in  the  tar  carbolic 
liquid,  in  holes  dug  in  the  ground  with  tanks  built  in 
the  same,  and  left  in  there  for  several  days ; then  taken 
out,  and  undergoing  the  other  process  of  silicate  of 
soda,  limewasli  and  chloride  of  calcium,  as  described, 
will  render  them  proof  against  fire  and  dry  rot. 


164 


CEMENTS. 


The  Silica  Cement,  a Peeseryative  to  the  Bottom 
OF  Iron  Ships. 

It  is  well  known  that  iron  ships  have  produced 
many  disasters  from  rusting  after  long  voyages ; the 
experiments  tried  for  preventing  the  adherence  of 
barnacles  and  the  rusting  have  been  very  numerous. 
The  author  feels  quite  confident  of  success,  by  the  pro- 
per application  of  a silica  cement  prepared  by  a hot 
solution  of  asphaltum  and  fine  sand,  manganese  and 
liquid  silicate  of  soda,  and  putting  it  on  the  bottom  of 
the  iron  ships  by  means  of  a brush,  and  before  becom- 
ing quite  dry,  to  dust  over  the  paint  more  powdered 
manganese. 

The  Most  Adhesive  Lubricator. 

Black  lead,  6 lbs.,  are  mixed  with  3 lbs.  slaked 
lime;  8 lbs.  sulphate  of  baryta  are  mixed  with  7 lbs. 
of  linseed  oil ; the  whole  mass  is  well  mixed  togetlier 
to  a uniform  consistency,  and  the  entire  mass  made 
more  plastic  with  concentrated  solution  of  silicate  of 
soda.  This  cement  may  be  used  for  numerous  pur- 
poses, where  hardness  and  adhesiveness  are  the  desired 
objects,-*uniting  at  the  same  time  steam  and  hot  water. 
For  locomotives,  engines  and  machinery  it  is  prepared 
from  a mixture  of  silicate  of  soda  liquid,  at  25°  B., 
added  to  fine  plumbago,  talc  and  asbestos  in  equal 
quantities,  so  as  to  retain  the  thin  plastic  condition, 
and  capable  of  dropping  it  on  the  journals  in  very 
small  portions. 

The  Cheapest  Whitewash,  which  is  very  durable 
for  indoor  and  outdoor  work,  is  prepared  by  the  fol- 


CEMENTS. 


1G5 


lowing  composition  : To  1 lb.  slaked  lime  and  1 lb. 
sulphate  barjta,  add  1 pint  of  silicate  of  soda  and  1 
pailful  of  hot  water  ; stir  the  materials  well  together, 
and  use  it  at  once.  If  the  color  is  intended  for  a 
yeliow  wash,  add  a quarter  of  a lb.  chrome  yellow  ; 
if  for  a blue  wash,  use  instead  of  the  latter  a quarter 
of  a lb.  of  ultramarine,  (worth  six  cents  ;)  and  if  the 
paint  is  intended  to  coat  iron  railing,  stoves,  steam- 
boat chimneys,  and  to  obtain  a brown  or  black  fire- 
proof paint,  add  half  a pound  of  manganite,  an  oxide 
of  manganese,  or  the  pyrolusite,  which  is  the  black  or 
gray  peroxide  of  manganese. 

The  white  wash  or  yellow  wash  just  quoted  is  ex- 
tremely durable  and  cheap  for  wmoden  fences  along 
rail-road  tracks,  canal  boats,  farm  houses,  and  other 
wooden  structures. 

The  Most  Durable  Aquarium  Cement. 

The  materials  of  a water-resisting  composition  are 
prepared  by  mixing  finely  powdered  dry  silicate  of 
soda,  powdered  chalk,  and  fine  sand  in  equal  quan- 
tities, made  plastic  with  the  liquid  silicate,  and  ap- 
plied at  the  joints,  and  worked  over  with  fiuid  chlo- 
ride of  calcium,  and  when  quite  dry  let  some  weak 
hydrofluoric  acid  pass  over  tlie  cemented  joints.  This 
cement  will  be  permanently  impervious  to  water,  and 
will  not  crack.  The  same  composition  is  quite  suita- 
ble for  breweries,  malt  houses,  linings  for  water-tanks, 
and  cellars  into  which  water  flows. 

The  author  considers  it  advisable  to  show,  also,  the 
advantages  of  concrete,  by  quoting  Tail’s  system,  ap- 
plied in  Paris,  and  the  description  of  the  concrete 

8^ 


166 


CEMENTS. 


bridge  at  London,  and  will  state,  that  the  addition  of 
silicate  of  soda  to  the  concrete  will  undoubtedly  en- 
sure a great  saving. 

The  material  consists  of  one  part  of  Portland  cement 
to  eight  parts  of  coarse  gravel.  The  cement  and  gravel 
are  tirst  well  mixed  together  in  a dry  state,  and  when 
this  is  done  it  is  damped  by  means  of  a large  watering 
pot,  containing  some  hot  silicate  of  soda,  and  again 
mixed  by  a pronged  drag,  such  as  is  used  for  dragging 
dung  out  of  a cart,  until  the  entire  heap  has  been 
wetted  and  mixed  together.  It  is  then  put  in  iron  or 
zinc  pails  and  poured  into  the  frame,  where  it  is 
leveled  by  men  stationed  for  the  purpose.  In  order 
to  save  concrete,  large  lumps  of  stones  or  brickbats 
are  put  into  the  centre  of  the  wall,  and  covered 
over  and  about  with  concrete.  Frost  does  not  affect 
the  concrete  after  it  has  once  set,  which,  with  good 
cement,  will  be  in  about  five  or  six -hours.  JSTor 
do  heavy  rains  appear  to  injure  it  in  the  slightest 
degree,  though  they  may  chance  to  fall  ere  the  con- 
crete has  hardened.  The  walls  can  be  made  straight 
and  even  as  it  is  possible  for  walls  to  be,  and  the 
corners  as  sharp  and  neat  as  if  the}^  had  been  formed 
of  the  most  carefully  dressed  stone. 

The  Soluble  Glass  as  Manure  for  Grapevines. 

By  putting  the  dry  silicate  of  soda  at  the  roots  of 
grapevines,  with  or  without  the  addition  of  phosphate 
of  lime,  has,  by  experiments,  proved  of  immense  benefit 
to  the  thriving  of  the  vines  to  a proper  thickness,  and 
the  grapes  of  uncommon  size. 


CEMENTS. 


167 


The  Soluble  Glass  a Substitute  for  Glue. 

It  has  proved  quite  useful  in  applying  the  liquid 
glass  for  glueing  wood  and  paper  together,  instead  of 
the  common  glue,  and  it  is  sold  in  the  trade  as  mu- 
cilage, and  applied  on  pasteboard  instead  of  emery 
or  corundum  paper,  used  by  cabinet-makers  and  other 
mechanics  for  polishing.  As  a paste  for  book-binders 
instead  of  glue,  starch  or  dexterine,  it  has  proved 
quite  useful.  Earthenware  may  be  kept  more  durable 
by  lining  them  with  a weak  solution.  It  is  likewise 
used  on  leather,  provided  the  same  is  not  exposed  to 
much  ben  din  O’. 

The  glazing  or  enameling  of  culinary  vessels,  made 
either  for  iron  or  stone  ware,  the  soluble  glass  is  use- 
fully applied  in  the  following  manner : 

The  silicate  solution  of  soda  and  potash  is  mixed 
with  thick  lime  water;  to  100  parts  of  the  silicate  add 
1 part  of  lime  water,  made  from  1 part  caustic  lime  to 
6 parts  of  water.  The  mixture  is  then  evaporated  to 
dryness  and  reduced  to  fine  powder.  By  dipping 
first  the  objects  to  be  glazed  in  the  liquid  silica,  the 
powder  is  then  sifted  over  them ; when  dry,  the 
operation  is  repeated  again  ; when  dry,  the  coating 
becomes  so  hard  that  it  cannot  be  rubbed  off  by  the 
hands  ; they  are  then  treated  like  other  ware  by 
putting  them  in  a furnace,  requiring,  however,  not  a 
very  great  heat. 

A similar  process  is  to  prepare  a mass  from  100 
parts  powdered  quartz,  80  parts  pure  potash,  10  parts 
saltpetre,  and  20  parts  slaked  lime,  which  mixture 
is  made  into  a thin  paste  with  the  liquid  silicate,  and 
then  burnt.  This  glazing  is  very  durable,  and  resists 


168 


CEMENTS. 


both  vegetable  and  mineral  acids  like  common  glass. 
It  requires  no  great  skill  to  execute  the  operation, 
and  the  expense  to  prepare  such  a glazing  is  but  a 
trifle. 

Soluble  Glass  Application  for  Yarious  Cements. 

Porcelain^  Glass  and  Metals  are  fastened  together 
when  broken,  either  by  the  liquid  or  gelatinous  silicate 
b}^  the  following  method : Heat  the  object  to  be 
fastened  together  to  that  of  boiling  water,  and  apply 
the  soluble  glass  on  both  sides  of  the  fracture,  press 
them  together  and  leave  them  in  a warm  place  for  a 
fortnight,  when  they  will  be  flt  for  use.  Fluorspar 
finely  ground,  black  oxide  of  manganese,  oxide  of  iron, 
(crocus,)  finely  powdered  soluble  glass,  and  many  more 
refractory  substances  are  suitable  articles  to  mix  with 
the  liquid  silica  for  the  various  cements  in  use.  A 
cement  for  fastening  iron  in  stone,  glass  or  wood  is 
recommended,  consisting  in  1 part  prepared  chalk,  1 
part  marble  dust,  and  made  plastic  with  the  liquid 
silica,  or  1 part  powdered  soluble  glass,  2 parts  pow- 
dered fluorspar,  made  into  a paste  with  the  liquid 
silica,  and  this  is  for  pasting  labels  on  glass  bottles. 

Caseine^  or  metamorphosed  milk,  is  also  mixed  with 
the  liquid  silica,  and  makes  an  excellent  paste. 

Firejproof  Cement  is  composed  of  the  various  oxides 
of  iron,  and  formed  into  a paste  with  the  liquid 
silica. 

The  Athens  Marlle  Cement  is  composed  of  carbon- 
ate of  lime,  carbonate  of  magnesia  and  silica  with 
oxide  of  iron,  and  made  into  a thin  liquid  and  applied 
to  tli^  stone,  which,  on  drying,  is  permanently  fastened 


CEMENTS. 


169 


to  the  surface,  and  protects  it  from  smoke,  dust  and 
atmospheric  agents. 

Common  and  fire  brick  acquire  great  strength  if  the 
silicate  of  soda  has  been  employed  in  the  manufacture, 
and  become  indestructible;  they  are  then  particularly 
fit  for  bakers’  ovens,  wall  and  w^ell  foundations  and 
furnace  beds. 

Glazed  Pajper  for  apothecaries’  use,  may  likewise 
be  prepared  with  the  soluble  glass. 

Metallic  Cement  is  formed  of  a mixture  of 
equal  parts  of  oxide  of  zinc,  peroxide  of  manganese 
and  litharge,  and  made  up  with  liquid  silica  and 
marble  dust,  and  applied  between  the  metals  to  be 
cemented. 

An  Impeemeable  Cement  Eesisting  Steam. 

It  is  prepared  by  mixing  six  parts  finely  powdered 
black  lead,  3 parts  slaked  lime,  and  8 parts  of  Plaster 
of  Paris,  made  into  consistency  by  the  liquid  silica. 

Zinc  Cement^  for  stopping  cracks  in  metallic  appa- 
ratus and  other  materials,  is  made  by  mixing  equal 
weights  of  zinc  white  and  finely  powdered  soluble 
glass  with  a solution  of  chloride  of  zinc  of  the  den- 
sity of  126  ; it  sets  rapidly  and  resists  the  action  of 
most  agents.  The  simple  mixture  of  oxide  of  zinc 
with  a solution  of  the  chloride  of  zinc,  has  also  been 
recommended. 

The  Gypsum  and  Clay  Cement. 

This  cement  is  very  hard,  and  is  prepared  by  an  in- 
timate mixture  with  liquid  silica,  after  the  gypsum 


170 


CEMENTS. 


has  been  calcined,  and  it  is  preferred  to  lime  cement, 
for  the  reason  that  by  the  action  of  fire,  it  becomes  re- 
converted into  lime,  which,  when  the  water  from  fire 
engines  is  brought  to  bear  upon  it,  expands  much,  and 
forces  out  the  walls  to  the  destruction  of  the  walls. 

Hard  Cement. 

It  consists  in  mixing  5 parts  powdered  clay,  2 parts 
iron  filings,  and  1 part  of  black  oxide  of  manganese, 
and  part  borax,  made  into  paste  with  liquid  silica; 
wdien  dry  is  very  hard,  and  withstands  water.  Also, 
a mixture  of  manganese  and  zinc  lohite  witli  Plaster 
of  Paris  forms  a very  hard  cement,  and  has  great  ad- 
hesive capacity. 

Drain  and  gas  pipes^  for  conducting  to  sewers  and 
houses,  may  be  made  as  permanent  as  iron  pipes  by 
using  a hard  cement,  consisting  of  hydraulic  lime,  clay 
and  sand,  mixed  with  fine  powdered  fluorspar  and 
soluble  glass,  all  made  plastic  by  the  liquid  silica  ; 
this  mass,  when  dry  and  burnt,  will  resist  a pressure 
of  600  pounds  to  the  square  inch,  while  iron  pipes 
burst  under  a pressure  of  40o  pounds  to  the  square 
inch. 

Cement  for  Closing  Cracks  in  Stoves. 

It  is  prepared  by  mixing  flnely  pulverized  iron,  such 
as  can  be  procured  at  the  druggists,  with  liquid 
water  glass,  to  a thick  paste,  and  then  coating  the 
cracks  with  it.  The  hotter  the  Are,  the  more  does 
the  cement  melt  with  its  metallic  ingredients,  and 
the  more  completely  will  the  crack  become  closed. 


CEMENTS. 


171 


Cement  for  a Cistern. 

Take  10  parts  of  Plaster  of  Paris. 

“ 2 “ Glauber  Salts. 

“ 4 ‘‘  Clay. 

“ 4 ‘‘  Slaked  Lime. 

Made  in  a plastic  cement  with  the  liquid  silicate  of 
soda,  and,  before  it  hardens,  add  liquid  chloride  of 
calcium. 

For  sweetening  the  water  in  cisterns^  which  is  found 
to  be  hard,  may  be  made  soft  by  one  gallon  of  silicate 
of  soda  in  the  cistern,  and  repeat  the  operation  once 
a month. 

The  hest  iron  cement  is  composed  of  calcined  plas- 
ter and  iron  tilings,  from  each  10  parts,  4 parts  oxide 
manganese,  2 parts  slaked  lime,  made  plastic  with  the 
liquid  silicate  of  soda. 

A Strong  Cement  for  Iron. 

To  4-5  parts  clay,  dry  and  powdered,  2 parts  iron 
tilings,  1 part  manganese,  \ part  salt,  ^ part  borax,  in 
a paste  made  with  soluble  glass,  or  equal  parts  zinc 
white  and  manganese,  made  to  a paste  ; must  be  used 
immediately. 

The  Peaslet  Cement. 

The  manufacturer  of  this  cement  has  made  himself 
celebrated  and  wealthy  by  his  perambulations  through- 
out the  United  States  with  a span  of  horses  attached 
to  a load  of  hay,  so  it  is  thought  advisable  to  en- 
lighten the  reader  with  its  composition: 

White  glue,  dissolved  in  a large  quantity  of  hot 
water,  also  50  parts  of  isinglass,  and  3 parts  of  gum 


172 


CEMENTS. 


arabic,  and  3 parts  of  gum  tragacanth,  and  to  this  solu- 
tion an  alcoholic  solution  of  white  shellac;  1 part  of 
the  latter  is  then  mixed  with  the  watery  solutign. 
To  the  whole  are  added  24  parts  of  white  lead,  and 
12  parts  of  glycerine,  and  200  parts  of  alcohol.  It  is 
immediately  put  in  bottles  and  well  corked.  In  other 
words  : 200  parts  white  glue,  parts  lead,  12  parts 
glycerine,  200  parts  alcohol,  50  parts  isinglass,  3 parts 
gum  arabic,  3 parts  gum  tragacanth,  1 part  bleached 
shellac. 

Iron  Cement  for  Water  and  Gas  Pipes  and  Castings. 

It  is  obtained  from  sixty  parts  cast  iron  turnings, 
mixed  with  two  parts  of  sal  ammonia,  one  part  fluor 
sulphur,  and  one  part  lime  cement  ; the  whole  made 
plastic  by  the  liquid  glass  just  before  using  it,  to  mend 
holes  of  whatever  description  in  iron  pipes  or  iron 
castings  ; it  becomes  soon  very  hard,  and  every  crevice 
is  filled. 

Cement  with  Liquid  Silica  for  all  Purposes. 

A good  cement,  which  will  stand  for  many  years 
without  any  paint.  Good  Portland  cement  is  always 
recognised  by  its  bright  color  of  bluish  tinge,  but  a 
common  cement  is  of  a dull  slate  color.  For  face 
work,  two  of  gravel  and  one  of  cement  is  the  best 
mixture ; with  the  finishing  coat,  half  and  half ; too 
much  cement  in  the  mixture  makes  it  too  rich,  and 
is  a common  cause  of  cracks  ; good  cement  should  be- 
come hard  the  second  day,  so  as  not  to  be  easily 
broken  ; that  which  will  crumble  in  the  fingers  on  the 
second  day  must  be  condemned  at  once. 


CEMENTS. 


173 


- Cement  intended  for  mouldings  should  be  mixed 
with  sharp  sand,  or  a smooth  finish  cannot  be  ob- 
tained. Portland  cement,  gravel  made  plastic  with 
the  liquid  silica,  ought  to  be  used  only  as  the  first 
coat,  but  not  on  the  finishing  coat ; if  rain  gets  to  it 
before  being  quite  dry,  it  is  very  liable  to  perish. 

Stone  Cement. 

Infusorial  earth  one,  and  litharge  one,  equal  parts, 
fresh  slaked  lime  one-half,  and  linseed  oil,  made  into 
a homogeneous  mass,  assume  the  hardness  of  sand- 
stone, suitable  to  fasten  iron  in  stone,  such  as  foun- 
tains, vases,  statuary,  and  in  small  quantity,  may  be 
used. 

Colored  Cements. 

To  a solution  of  silicate  of  soda  of  1.29S,  add,  while 
stirring,  first  pulverized  and  previously  washed  lixivia- 
ted chalk,  so  as  to  form  a thick  mass,  to  which  are 
added  for  coloring  purposes  the  following  substances  : 

Por  black,  sulphuret  of  antimony. 

Gray,  iron  filings. 

Gray  white,  zinc  dust. 

Bright  green,  carbonate  of  copper. 

Blue,  orange  and  red,  cobalt,  vermilion  and  car- 
mine. 

This  cement  hardens  in  six  to  eight  hours,  and 
bears  polishing  like  marble. 

Coating  for  Outside  Walls. 

The  following  coating  for  rough  brick  walls  is  used 
by  the  United  States  Government  for  painting  light- 


174: 


CEMENTS. 


houses,  and  it  eifectually  prevents  moisture  from  strik- 
ing through  : Take  of  fresh  Hosendale  cement  three 

parts,  and  of  clean,  fine  sand  one  part ; mix  with 
fresh  water  thoroughly.  This  gives  a gray  or  granite 
color,  dark  or  light,  according  to  the  color  of  the  ce- 
ment. If  brick  color  is  desired,  add  enough  Venetian 
red  to  the  mixture  to  produce  the  color.  If  a very 
light  color  is  desired,  lime  may  be  used  with  the  ce- 
ment and  sand.  Care  must  be  taken  to  have  all  the 
ingredients  well  mixed  together.  In  applying  the 
wash,  the  wall  must  be  wet  with  clean  fresh  water; 
then  follow  immediately  with  the  cement  wash.  This 
prevents  the  bricks  from  absorbing  the  water  from 
the  wash  too  rapidly,  and  gives  time  for  the  cement 
to  set.  The  wash  must  be  well  stirred  during  the 
application.  The  mixture  is  to  be  made  as  thick  as 
can  be  applied  conveniently  with  a whitewash  brush. 
It  is  admirably  suited  for  brick-work,  fences,  etc.,  but 
it  cannot  be  used  to  advantage  over  paint  or  white- 
wash. 

Peeservation  of  Stones. 

Dr.  Robert,  in  the  Paris  ‘‘  Les  Mondes,”  maintains 
that  the  use  of  the  black  oxide  of  copper,  and  its  salts, 
will  effectually  prevent  change  in  stone.  He  shows 
that  the  decay  of  granite,  marble,  limestones,  sand- 
stones, and  all  natural  building  stones,  is  the  combined 
effect  of  various  causes,  and  that  among  these  is  a 
very  minute  lichen,  the  Lejpra  antiquitalis^  which  is 
one  of  the  worst  enemies  of  stone,  and  its  action  is 
to  such  an  extent  that,  for  instance,  the  beautiful 
marble  sculptures  of  the  well-known  Parc  de  Ver- 
sailles will,  unless  proper  measures  be  taken  for  stay- 


CEMENTS. 


175 


ing  the  process  of  decay,  be  unsightly  and  ugly  masses 
of  dirt,  and  quite  irretrievably  lost,  as  works  of  art, 
within  the  next  50  years.  The  author,  taking  as  in- 
stances such  buildings  at  Paris  as  the  Bourbon  Palace, 
the  Palais  du  Corps  Legislatif,  the  Mazarin  Palace, 
{V Institute)  the  Mint,  and  others,  points  out  that  dust, 
spiders’  webs,  and  the  action  of  rain,  combined  with 
the  minute  lichen  above  alluded  to,  hasten  the  decay 
of  stone,  especially  of  those  parts  where  any  sculpture 
or  ornamental  carving  promotes  the  deposition  of  dirt 
and  dust.  Various  places  and  instances  are  cited  of 
the  application  of  oxide  of  copper  and  its  salts,  which 
places  are  open  to  inspection  ; and  the  length  of  time 
which  has  elapsed  since  such  application,  seems  to 
warrant  the  conclusion  that  these  compounds  act  as 
preservatives  of  stone.  In  reference  to  granite,  the 
author  states  that  this  stone  is  also,  according  to  the 
experience  of  Egyptian  engineers,  far  more  readily 
affected  by  a moist  climate  than  one  would  be  led  to 
believe.  The  obeLsk  of  Luxur,  brought  from  Upper 
Egypt  to  Paris,  has  become  blanched  and  full  of  small 
cracks  daring  the  40  years  it  has  stood  on  the  Place 
de  la  Concorde  ; although  40  centuries  had  not  per- 
ceptibly affected  it  as  long  as  it  was  in  Egypt.  Granite 
in  a moist  climate  becomes  the  seat  of  a minute  cryp- 
togamic  plant,  which  greatly  aids  its  destruction  ; and 
it  is,  moreover,  a well-known  fact,  that  the  disintegra- 
tion of  this  stone,  which  is  composed  of  three  separate 
minerals,  (quartz,  mica  and  felspar,)  depends  very 
greatly  upon  the  thorough  and  intimate  mixture,  as 
well  as  the  chemical  composition,  of  these  three  in- 
gredients, each  of  which,  in  a separate  state,  more 
easily  withstands  the  inffuence  of  the  weather. 


176 


CEMENTS. 


Preseryation  of  Stone  by  Silica. 

The  Yictoria  stone  seems  to  have  endured  severe 
tests  and  to  promise  well.  The  process  by  which 
it  is  made  consists  in  mixing  broken  granite  with 
hydraulic  cement,  and  steeping  the  whole,  when 
set,  in  a solution  of  silica.  The  granite  used  is  the  re- 
fuse of  the  quarries,  and  is  broken  up  at  the  works. 
It  is  then  mixed  with  Portland  cement,  in  propor- 
tions of  four  of  granite  to  one  of  cement,  sufficient 
water  being  added  to  give  it  a pasty  consistency.  In 
this  state  it  is  placed  in  moulds,  when  it  consolidates 
in  about  four  days.  When  taken  from  the  moulds  it 
is  placed  for  two  days  in  a solution  of  silicate  of  soda, 
which  completes  the  process. 

The  silicate  solution  is  prepared  in  a peculiar  man- 
ner, and  upon  it  the  success  of  the  operation  depends. 
The  silicate  of  soda  has  the  property  of  hardening  any 
kind  of  concrete  in  which  lime  is  a component.  This 
substance  has  been  hitherto  too  costly  for  general  use 
in  artificial  stone  manufacture,  and  it  becomes  caustic 
by  the  absorption  of  its  silica,  so  that  it  attacks  the 
hands  of  the  workmen. 

A Strong  Metallic;  Cement. 

It  is  intended  to  cement  or  unite  metals  together, 
and  which  hardens  rapidlj^ ; may  be  made  by  stirring 
the  finest  Paris  white  in  a solution  of  silicate  of  soda 
at  B.,  so  as  to  form  a plastic  mass,  which  may  be 
colored  by  the  oxide  of  manganese,  or  sulphuret  of 
antimony,  or  iron  filings  or^iinc  dust.  Carbonate  of 
copper  gives  a green  color,  oxide  of  chrome  a dark 
green,  red  lead  an  orange,  vermilion  a scarlet,  and 


CEMENTS. 


ITT 


carmine  a violet  color.  After  the  application  between 
the  metals  to  be  joined,  the  cement  may  be  polished, 
and  acquires  a metallic  lustre.  It  may  also  be  em- 
ployed for  the  permanent  repair  of  zinc  ornaments. 

The  Latest  Chinese  Waterproof  Composition. 

Schoicao  is  a composition  used  in  Pekin  for  cover- 
ing straw"  baskets,  which  are  intended  to  carry  oil  for 
long  distances.  Cardboards,  when  covered  with  it, 
become  as  hard  as  Avood.  Most  w^ooden  buildings  in 
the  capital  have  a coating  of  it.  The  original  w^as 
made  of  3 parts  of  blood  deprived  of  its  febrine,  4 parts 
of  lime  and  a little  alum,  and  'by  adding  2 parts  of 
liquid  silicate  of  soda,  will  improve  the  mass  very 
much. 

The  most  refractory  cement  is  formed  from  silica^ 
asbestos^  flumbago  and  soajystone.  These  materials, 
mixed  in  certain  proportions  and  made  plastic  by  the 
liquid  silica,  form  a most  valuable  cement  for  loco- 
motive journals  and  otlier  lubricating  purposes,  for 
lining  of  steam  boilers  as  well  as  coating,  for  tilling 
up  airholes  in  iron  castings.  By  the  addition  of  per- 
oxide of  manganese,  it  may  be  much  improved,  and 
serve  as  a permanent  paint,  which  is  fire  and  w^ater- 
proof. 


ARTIFICIAL  STONE. 


The  following  notice  of  artificial  stone  has  been 
taken  from  the  Keport  of  the  U.  S.  Commissioner  to 
the  Paris  Exposition  of  1867  : 

The  agglomerated  hetons  have  been  extensively  in* 
troduced  in  France  in  the  construction  of  heavy  pub* 
lie  works,  and  in  the  erection  of  private  dwellings, 
Nearly  forty  miles  of  the  sewers  of  Paris  have  been 
constructed  wholly  of  this  material.  All  the  founda* 
tions  and  basements  of  the  palace  of  the  Exposition, 
and  other  heavy  structures  in  the  Champ  de  Mars, 
those  of  the  immense  military  barrack  recently  erected 
on  the  island  of  the  city,  the  raihroad  bridge  of  Ste. 
Colombo  on  the  road  from  Lyons  to  Marseilles,  a very 
large  number  of  substructures  for  private  houses,  some 
houses  entire,  and  innumerable  foundations  for  the 
support  of  heavy  machinery,  have  been  constructed  in 
the  same  way. 

The  manufacture,  as  now  generally  practiced,  was 
originated  by  Mr.  Coignet,  a French  engineer,  whose 
name  is  generally  associated  with  the  process.  The 
following  particulars  in  regard  to  the  Coignet  Mton 
are  gathered  from  several  sources,  the  most  interesting 
being  derived  from  a paper  on  the  subject,  published 
by  Mr.  A.  Paul,  civil  engineer,  of  Paris. 

This  substance  is  compounded  of  sand  in  large  quan- 
tity, with  lime  in  smaller,  say  in  the  proportion  of  five 


AUTmCIAL  STOKE. 


179 


to  one,  more  or  less,  and  also,  if  rapid  setting  and  nn- 
nsiial  hardness  are  desired,  with  a quantity  of  cement, 
hardly  more  than  one-quarter  of  the  quantity  of  lime, 
the  proportions  being  estimated  by  volume  and  not  by 
weight.  This  mixture,  in  a condition  nearly  dry,  and 
reduced  to  the  form  of  a stiff  paste,  by  being  ground 
and  worked  up  in  mills  constructed  for  the  purpose, 
is  introduced  into  the  moulds  designed  to  give  it  form, 
and  compacted  by  repeated  blows  of  a heavy  rammer. 
The  result  is  the  production  of  a copy  firm  enough  to 
allow  the  removal  of  the  mould  at  once,  by  the  separa- 
tion of  its  parts.  The  copy  is  perfect,  since  the  yield- 
ing material,  under  the  heavy  impact  of  the  ram,  has 
been  driven  into  all  the  minute-lines  of  the  mould,  and 
all  the  delicate  traceries  of  the  ornamental  work.  On 
exposure  to  the  air  the  block  rapidly  hardens,  and  it 
has  soon  all  the  solidity  of  natural  stone. 

The  effect  of  the  successive  processes  of  grinding  and 
ramming  is  singularly  to  increase  the  specific  gravity 
of  the  product.  The  reduction  of  volume,  when  the 
bulk  of  the  compacted  mass  is  compared  with  that  of 
the  materials  out  of  which  it  is  composed,  is  nearly  as 
two  to  one,  (1.7  to  one,)  and  the  weight  per  cubic  foot 
becomes  about  one  hundred  and  forty  pounds.  Simul- 
taneously with  the  increase  of  weight,  there  occurs  a 
very  remarkable  increase  of  strength  ; the  resistance 
of  many  specimens  to  compression  amounting  to  more 
than  two  and  a half  tons  to  the  square  inch.^  An  or- 
dinary mortar,  made  with  precisely  the  same  materials, 


* Specimens  of  very  superior  betons  Lave  even  resisted  crusbing 
pressures  approaching  to  four  tons  per  square  inch  of  section. 


180 


ARTIFICIAL  STONE. 


will  be  crushed  by  a pressure  of  probably  less  than 
five  hundred  pounds. 

The  explanation  of  this  greatly  increased  cohesive 
strength  may  perhaps  be  found  in  the  following  con- 
siderations : 

In  mixing  mortar  an  excess  of  water  is  always  em- 
ployed, and  this  occupies  much  space,  and  by  separat- 
ing the  molecules  of  lime  prevents  their  union,  or  acts 
unfavorably  to  what  is  called  the  setting  of  the  mor- 
tar. If  we  suppose  this  setting,  in  the  case  of  lime  or 
cement,  to  be  an  actual,  though  perhaps  confused, 
crystalization,  whether  of  hydrate  of  lime,  or  of  the 
silicate  and  aluminate  of  lime,  mixed  or  combined, 
which  constitute,  in  different  proportions,  hydraulic 
limes  and  cements,  it  follows  that  this  crystalization 
will  be  so  much  the  more  energetic  in  measure  as  the 
water  present  in  the  mortar  in  excess  during  the  pre- 
paration is  more  effectually  eliminated,  and  that  in 
the  same  proportion  the  union  of  the  sand,  lime  and 
cement  will  be  more  intimate. 

It  is  the  opinion  of  the  engineer  whose  paper  has 
been  cited  above,  that  the  hardening  of  the  compacted 
mass  is  not  exclusively  due  to  the  physical  properties 
of  the  lime  and  cement  in  their  original  condition,  but 
is  owing  also,  in  a measure,  to  the  conversion  of  these 
substances  gradually  into  carbonates,  and  that  this 
conversion  goes  on  the  more  rapidly  and  becomes  the 
more  complete  in  proportion  as  the  lime  is  more  finely 
divided. 

Hydraulic  lime  should  be  used  in  this  preparation. 
Fat  lime  may  be  employed,  provided  that  a sufiicient 
proportion  of  cement  be  added  to  give  it  the  hydraulic 
character.  The  lime  should  be  well  burned ; lumps 


ARTIFICIAL  STONE. 


181 


which  seem  to  be  overburned  or  underburned  must  be 
rejected.  It  is  slaked  by  sprinkling,  and  afterwards 
heaped  up  and  allowed  to  lie  some  days  in  order  that 
it  may  acquire  its  maximum  of  volume  and  become 
thoroughly  disintegrated.  It  is  then  sifted  through 
Ho.  35  wire  gauze.  In  this  powdered  condition  the 
slaked  lime  may  be  kept  for  lengths  of  time. 

It  has  been  proved  by  the  inventor,  Mr.  Coign et, 
that  all  kinds  of  lime,  even  the  most  common,  after  a 
while  become  as  hard  as  the  best.  The  only  difference 
is  in  the  promptness  of  the  setting.  In  explanation  of 
this  fact,  it  is  suggested  that  the  ultimate  hardness  is 
probably  due  to  the  formation  of  the  carbonate. 

The  cements  employed  in  the  manufacture  of  these 
hetons  are  in  general  the  heavy  and  slow  setting 
cements.  The  sand  preferred  is  river  sand,  mixed 
with  particles  of  stone  of  from  one  to  five  millimetres 
in  diameter.  If  the  sand  is  too  coarse,  the  resulting 
masses  will  be  rough ; if  too  fine,  it  ssparates  too 
much  the  molecules  of  the  lime,  retards  the  setting, 
and  is  prejudicial  to  the  strength  and  durability  of  the 
resulting  product.  Pit  sand  answers  very  well ; but 
in  order  to  produce  a result  equal  to  that  obtained 
with  river  sand,  it  is  necessary  to  increase  the  propor- 
tion of  lime  and  cement. 

In  mixing  the  materials,  they  are  rudely  measured, 
spread  out  on  the  ground,  and  turned  with  a shovel 
until  the  mass  becomes  homogeneous.  They  are  then 
introduced  into  a tempering  mill,  and  subjected  to  a 
very  energetic  grinding ; water  being  added  sparingly 
from  time  to  time,  and  only  in  sufficient  quantity  to 
give  the  m'ass  cohesiveness,  and  bring  it  to  the  form 
of  a paste  as  stiff  as  can  be  conveniently  worked.  The 

9 


182 


ARTIFICIAL  STONE. 


importance  of  this  part  of  the  operation  is  very  great, 
since  the  rapidity  of  the  setting  and  the  degree  of  the 
ultimate  hardness  will  depend  upon  the  minute  sub- 
division, which  is  the  effect  of  the  grinding  in  the  mill 
of  the  particles  of  lime  and  cement. 

The  tempering  mill  is  one  which  has  been  con- 
structed specially  for  this  purpose.  It  is  of  rolled 
iron,  cylindrical  in  form,  and  has  a vertical  arbor  in 
the  centre,  armed  with  knives  set  spirally  around  it. 
At  the  bottom,  the  cylinder  is  perforated  with  many 
holes,  through  which  the  material  is  expelled  by  the 
pressure  of  a cycloidal  appendage  attached  to  the  arbor 
below  the  knives.  The  rapidity  of  the  expulsion  may 
be  controlled  by  raising  or  depressing  a cylindrical 
gate,  resembling  the  gate  of  the  Fourneyron  turbine, 
the  process  being  retarded  as  the  number  of  holes  un- 
covered is  diminished.  As  the  tempered  heton  is  ex- 
pelled in  the  plastic  condition  at  the  bottom,  additions 
are  made  to  the  quantity  in  the  mill  by  introducing 
raw  material  at  the  top. 

The  plastic  heton  thus  obtained  is  thrown  into  the 
moulds  in  strata  of  from  one  to  three  inches  thick,  and 
beaten  down  and  compacted  by  repeated  blows  of  a 
heavy  ram,  weighing  from  fifteen  to  twenty  pounds, 
applied  all  over  the  surface.  The  beating  of  a stratum 
having  been  completed,  its  surface  is  scratched  and 
roughened  by  means  of  a rake,  for  the  purpose  of  form- 
ing a secure  bond  with  the  stratum  next  to  follow. 

Two  kinds  of  moulds  are  employed,  according  as  the 
object  moulded  is  to  remain  permanently  in  the  spot 
where  it  is  formed,  or  is  to  be  removed  and  built  into 
a structure  elsewhere.  In  the  first  case,  the  moulds 
are  a species  of  coffer  built  up  temporarily  of  wooden 


artificial  stone. 


183 


walls  united  by  horizontal  cross-pieces,  which  are 
secured  by  bolts.  To  the  interior  of  these  coffer  walls 
may  be  affixed  the  moulds  necessary  to  produce  archi- 
tectural forms,  or  the  ornaments  and  decorations  of 
staircases,  portals,  windows,  &c.,  so  that  entire  walls 
ma}^  be  built  in  mass,  with  every  appearance  of  being 
sculptured  out  of  stone.  For  the  preparation  of  por- 
table blocks,  the  moulds  are  more  varied  in  construc- 
tion. They  take  the  form  of  every  description  of  ob- 
ject of  which  stone  is  the  usual  material,  and  serve  to 
produce  vases,  urns,  busts,  statues,  or  simple  cornices 
and  friezes. 

The  following  proportions  are  given  by  Mr.  Faul  as 
those  employed  in  the  great  monolithic  structures  of 
Paris,  including  the  sewers  and  the  substructures  of 
the  Exposition,  viz. : five  parts  of  sand,  one  of  lime, 
and  one-quarter  of  one  part  of  cement  in  bulk.  Such 
is  the  rapidity  with  which  constructions  in  this  ma- 
terial are  carried  on,  that  in  six  or  eight  hours  after 
beginning  work  on  a given  length  of  sewer,  it  becomes 
safe  and  practicable  to  remove  and  advance  the  cen- 
tres ; and  in  four  or  five  days  after  a section  has  been 
completed,  it  may  safely  be  turned  over  for  use. 

For  arches  with  a pitch  of  one  in  ten,  the  propor- 
tions are,  for  the  sand  and  lime  the  same  as  given 
above,  but  the  quantity  of  cement  is  doubled.  The 
groined  arches  of  the  ventilators  of  the  Exposition, 
and  of  the  substructures  of  the  gallery  of  refreshments 
surrounding  the  Exposition  palace,  were  constructed 
to  this  pitch,  and  thus  a floor  of  vast  dimensions  was 
supported  by  isolated  columns  one  foot  in  diameter 
and  distant  ten  feet  from  each  other  in  all  directions. 
At  the  crown  of  the  arches  this  floor  was  but  a little 


184 


AKTIFIOIAL  STONE. 


more  than  five  and  a half  inches  thick.  The  span  of 
the  basement  arches  of  the  city  barrack  is  nearly  twice 
as  great,  being  18.3  feet,  and  these  arches  are  built  to 
the  same  pitch.  At  the  crown,  in  this  case,  the  thick- 
ness of  the  material  is  nine  inches.  One  month  after 
the  completion  of  one  of  these  it  bore  a weight  of  forty- 
eight  thousand  kilograms  upon  twelve  square  metres 
of  surface,  or  of  forty-eight  tons  upon  a surface  of  ten 
feet  by  twelve. 

A church  has  been  constructed  at  Yesinet  of  this 
material  entirely,  the  whole  being  a mass  of  hetcm 
without  joints.  The  pit  sand  of  the  neighborhood 
was  used,  and  the  lime  and  cement  were  in  the  pro- 
portions first  given  above.  But  the  pavements  were 
made  of  a hUon  richer  in  cement ; the  quantity  of  this 
ingredient  being  made,  for  this  part  of  the  construc- 
tion, equal  to  that  of  lime.  These  pavements  were 
very  carefully  rammed  and  smoothed  with  the  trowel. 
In  the  lumber  mill  of  Aubervilliers,  the  arches  of  the 
substructure,  built  of  the  Coignet  heton^  are  twenty- 
eight  feet  in  span  and  fourteen  inches  thick  at  the 
crown.  All  the  machinery  of  the  saws  is  firmly  fas- 
tened to  the  floors  formed  by  these  arches,  by  means 
of  cramp-irons  secured  with  lead,  without  having  oc- 
casioned any  injury  to  the  structure  during  all  the 
time  the  mills  have  been  in  operation. 

The  most  important  of  the  benefits  which  are  to 
result  from  the  use  of  the  agglomerated  betms  is  pro- 
bably to  be  looked  for  in  the  superior  stability  and 
strength  which  they  are  destined  to  give  to  the  foun- 
dations and  basements  of  ordinary  dwelling-houses. 
The  usual  mode  of  forming  such  constructions  at  pres- 
ent is  to  employ  a certain  amount  of  cut  stone  at  inter- 


ARTIFICIAL  STONE. 


185 


vals,  and  to  till  up  the  intervening  spaces  with  nibble 
masonry.  The  entirely  dissimilar  character  of  these 
two  kinds  of  masonry,  with  the  great  number  of  bonds 
or  surfaces  of  junction  between  them,  produces  un- 
equal settling  and  the  consequent  cracking  of  the 
walls.  Walls  which  are  constructed  of  agglomerated 
heton  are  not  liable  to  such  accidents.  Their  whole 
mass  forms  but  a single  homogeneous  block,  stronger 
than  even  the  rock  on  which  it  rests  as  a foundation. 
From  the  fact  of  their  continuity,  their  weight  is  dis- 
tributed over  the  entire  area  of  the  foundation,  and 
no  settling  can  take  place  so  unequally  as  to  produce 
fracture. 

In  a dwelling  of  five  stories,  in  Miromesnil-street, 
Paris,  constructed  of  a single  mass  of  heton^  a staircase 
of  the  same  material  runs  in  helicoidal  form  from  the 
basement  to  the  highest  fioor,  moulded  in  the  position 
where  it  stands. 

At  the  Paris  Exposition  of  1867,  there  were  pre- 
sented specimens  of  the  various  applications  of  this 
important  material,  including  a pavilion,  as  illustrative 
of  its  adaptedness  to  building  in  mass,  lintels,  cornices, 
friezes,  paving  slabs,  troughs,  garden  benches  and  ta- 
bles, vases,  monuments,  urns,  statues  and  nearly  every 
other  important  object  in  which  stone  is  commonly 
employed,  whether  for  useful  or  for  ornamental  pur- 
poses. As  scarcely  ten  years  have  passed  since  Mr. 
Coignet’s  first  experiments  were  made,  and  as  it  is 
only  within  the  last  two  or  three  that  the  process  has 
been  perfected,  or  at  least  that  its  merits  have  been 
recognised,  the  heton  agglomerS  must  be  regarded  as 
one  of  those  new  and  useful  things  which  the  Expo- 
sition of  1867  was  first  to  bring  conspicuously  before 


186 


ARTIFICIAL  STONE. 


the  world.  At  the  Exposition  of  1862,  the  efforts 
which,  up  to  that  time,  had  been  made  in  this  direc- 
tion, inspired  in  the  jury  in  charge  of  the  subject  so 
little  confidence,  that  the  report  of  that  body  disposed 
of  them  all  in  the  following  summary  manner : “ Many 
artificial  stones  which  at  first  sight  appear  admirably 
adapted  for  this  purpose  [building]  are  found,  when 
exposed  to  this  unerring  test,  [actual  experience  of 
some  years,]  to  be  utterly  wanting  in  durability.  No 
artificial  stone  can,  therefore,  be  considered  durable 
as  compared  with  natural  stone  until  it  has  undergone 
the  test  of  long  experience;”  a test  which  the  jury 
were  not  disposed  to  think  had  as  yet  been  satisfac- 
torily sustained  by  any  such  composition  known  to 
them. 

The  crushing  weight  which  the  hHon  of  Mr.  Coignet 
is  capable  of  resisting  has  been  stated  at  four  hundred 
kilograms  per  square  centimetre,  or  nearly  fifty-four 
hundred  pounds  to  the  square  inch.  Its  resistance  to 
a force  of  tension  is  thirty  to  forty  kilograms  the  square 
centimetre,  or  four  hundred  to  five  hundred  and  forty 
pounds  per  square  inch. 

Experiments  at  Marseilles  and  at  Cherbourg. 

The  results,  on  the  whole,  are  interesting  and  sug- 
gest the  following  conclusions : 

1.  Common  lime  can  be  substituted  for  hydraulic 
lime  in  beton-coignet,  with  an  equally  durable  result, 
provided  the  blocks  are  allowed  to  harden  for  a few 
days  on  land  previous  to  immersion. 

2.  Blocks  of  beton-coignet  (sand  and  hydraulic  lime) 
can  be  made  in  direct  contact  with  the  sea,  provided 


ARTIFICIAL  STONE. 


187 


they  be  protected  by  a crib  during  the  time  necessary 
for  the  taking,  say  21  hours.  Blocks  thus  made  have 
proved  as  durable  as  those  made  on  shore  ; while  under 
similar  circumstances  of  immediate  immersion  in  the 
sea,  and  21  hours’  protection  by  a crib,  blocks  of  ordi- 
nary concrete  (sand,  hydraulic  lime,  and  stones)  made 
with  the  same  h^^draulic  lime,  would  disappear  in  a 
short  time. 

3.  Blocks  of  beton-coignet  made  on  land  are  quite 
ready  for  immersion  after  drying  and  hardening  for 
three  or  four  days,  while  blocks  of  hydraulic  concrete 
usually  require  from  three  to  six  months  for  drying 
and  hardening. 

To  supply  the  daily  demand  for  these  blocks  of  con- 
crete in  the  construction  of  a breakwater,  large  yards 
are  necessary,  which  are  usuall}^  at  a distance  from 
the  breakwater.  They  must  have  space  for  1,000  to 
2,000  blocks  in  various  stages  of  fabrication  and  dry- 
ing ; they  require,  also,  a large  establishment  of  ma- 
ehinery  and  railways ; a large  capital  is  thus  invested 
and  the  expense  is  heavy. 

In  making  beton-coignet  less  machinery  and  plant, 
less  ground  for  drying,  less  preparation  in  advance  are 
required,  the  time  and  capital  involved  are  less,  and 
the  whole  cost  is  consequently  diminished. 

Mr.  Coignet  now  proposes  the  construction  of  piers 
and  breakwaters  in  the  following  manner  : 

1.  Blocks  of  beton  to  be  made  on  land,  in  length 
equal  to  the  breadth  of  the  pier  and  of  corresponding 
size,  weighing  say  140  tons,  to  be  lowered  into  the  sea, 
and  placed  side  by  side,  across  the  line  of  the  pier,  for 
foundation. 

2.  The  wall  to  be  constructed  likewise  of  beton,  in 


188 


ARTIFICIAL  STONE. 


place,  forming  thus  a single  mass,  binding  the  blocks 
below  by  the  weight  and  solidity  of  the  wall. 

For  this  he  would  use  from  five  to  seven  parts  of 
sand,  one  of  lime,  fat  or  slightly  hydraulic,  and  one- 
fourth  to  one-half  part  of  cement. 

But  it  is  not  probable  that  the  government  engineers 
consider  the  experience  already  gained  sufficient  to 
warrant  them  in  recommending  so  great  an  outlay  at 
present  as  this  experiment  involves. 

The  materials  of  beton-coignet  exist  in  abundance 
in  all  countries  and  in  most  localities,  seldom  requir- 
ing long  and  expensive  transportation. 

Sand  is  easily  excavated,  lime  is  a simple  prepara- 
tion, and  both  are  materials  of  low  cost ; most  of  the 
labor  in  making  is  performed  by  machinery,  and  little 
of  the  manual  labor  required  need  be  skilled  labor. 

Sand,  lime,  water,  machinery,  motive  force,  few 
tools  and  common  labor,  are  the  elements  of  structures 
made  of  beton  ; and  the  beton  itself  is  well  adapted  to 
numerous  daily  wants,  in  which  solidity,  durability 
and  cheapness  are  preferable  to  beauty  of  materials, 
the  evidence  of  which  is  shown  in  the  ground  and  un- 
derground structures  of  the  great  palace  of  the  Expo- 
sition, and  in  its  increasing  application  to  sewers, 
tanks,  foundations,  floors,  walls,  &g. 

The  cost  of  beton  varies  with  that  of  the  lime  and 
cement  employed.  In  Paris,  works  in  beton  cost,  in- 
cluding fabrication  and  construction,  from  $5  to  $8 
per  cubic  yard.  Flagging,  two  inches  thick,  costs  56 
cents  per  square  yard. 


ARTIFICIAL  STONE. 


189 


Kansome  Artificial  Stone. 

If  Mr.  Eansome  has  not  found  the  philosopher’s 
stone,  he  has  at  least  produced  a stone  wortliy  a phi- 
losopher, and  which  promises  to  become  the  stone  of 
the  ages.  For  it  appears  to  have  elements  of  great 
durability,  and  it  certainly  possesses  every  other  quali- 
ty desirable  in  building  stone,  whether  for  structure 
or  ornament.  Although  five  years  are  not  five  centu- 
ries, chemistry  has  analyzed  even  the  tooth  of  time, 
and  can  produce,  within  the  period  of  a comparatively 
brief  experiment,  results  identical  with  those  of  ages 
of  atmospheric  corrosion  and  disintegration.  Mr.  Ean- 
some’s  stone  has  been  boiled,  and  roasted,  and  frozen, 
and  pickled  in  acids,  and  fumigated  with  foul  gases, 
with  no  more  effect  than  if  it  had  been  a boulder  of 
granite  or  a chip  of  the  blarney  stone.  It  has  been 
boiled  and  then  immediately  placed  on  ice,  so  as  to 
freeze  whatever  v/ater  might  have  been  absorbed,  and 
it  has  been  also  roasted  to  redness,  and  then  plunged 
in  ice  water,  but  without  any  sign  of  cracking  or 
softening,  superficially  or  otherwise.  JSTor  does  its 
durability  rest  alone  upon  such  evidence  as  this,  for  it 
is  of  the  simplest  chemical  composition  ; and  chemis- 
try and  geology  alike  testify  to  the  durability,  if  not 
the  indestructibility,  of  a stone  which  is  nearly  all 
silica,  like  Hint,  and  onyx,  and  agate,  and  jasper.  It 
has  no  oxydizable  constituent ; for  silica,  or  silicic  acid, 
is  already  oxydized,  and  thus  it  is  unalterable  in  air  ; 
and  as  the  new  stone  is  almost  impermeable,  it  will 
suffer  little,  if  any,  injury  from  moisture  or  frost. 

“ And  how  marvellous,  for  its  simplicity  and  beauty, 
is  the  process  by  which  this  stone  is  made ! Some 

9* 


190 


AETIFICIAL  STONE. 


toiling  mason  or  other,  hewing  in  the  quarry  or  in  ithe 
builder’s  yard,  must  have  wished,  before  now,  that 
stone,  like  iron,  might  be  melted  and  run  in  moulds, 
even  though  his  own  occupation  were  thus  at  an  end. 
Did  he  ever,  when  by  the  sea-shore  or  by  a sand-pit, 
think  of  cementing  indissolubly  together  the  countless 
millions  of  grains  into  solid  rock  ? Mr.  Ransome,  no 
mason,  however — unless  he  be,  as  he  may  be  for  any- 
thing we  know,  a member  of  the  mystic  brotherhood — 
did  think  of  this.  And  he  tried  every  cement  he 
could  lay  his  hands  to,  and  did  not  succeed.  The 
sand  became  little  else  than  mortar  by  such  sticking 
as  he  could  effect.  But  he  found  out,  at  last — and 
we  are  speaking  of  a time  more  than  twenty  years 
ago — that  the  best  sandstones  were  held  together  by 
silicate  of  lime.  And  so  he  set  himself  to  work  to 
produce  this  substance,  indirectly,  from  flints,  of  which 
plenty  could  be  found  for  the  purpose.  But  the  flints 
had  to  be  liquefled  flrst,  and  how  could  this  be  done  ? 
Not  by  heat,  nor  would  caustic  soda  touch  them,  so 
the  chemist  said.  Flints  might  be  boiled  in  a caustic 
solution  for  a week  together,  so  long  as  the  boiler  was 
an  open  one,  and  lose  very  little  by  the  operation. 
But  by-and-by  Frederick  Ransome  made  one  of  the 
most  unexpected  discoveries  in  chemistry,  viz.,  that 
when  boiled  in  a caustic  solution,  under  jpressure^ 
flints  would  melt  almost  like  tallow  before  the  Are. 
But  we  are  not  about  to  give  the  long  history  of  the 
invention.  With  flint  soup,  or  silicate  of  soda  as  a 
liquid,  the  question  was  what  other  liquid  would,  in 
mixing  with  it,  turn  both  into  an  enduring  solid  ? 
What  other  liquid  would  turn  both  into  silicate  of 
lime,  the  substance  he  was  seeking  ? When  he  found 


ARTIFICIAL  STONE. 


191 


that  chloride  of  calcium  (in  solution)  would,  when 
mixed  with  silicate  of  soda,  turn  both  into  flint,  or 
something  very  much  like  it,  the  road  was  clear,  and 
the  manufacture  of  stone  from  sand  was  as  simple 
and  as  beautiful  a process  as  the  making  of  Bessemer 
steel  from  pig-iron  by  blowing  air  through  it  when  in 
the  melted  state. 

“During  the  month  of  June,  1867,  on  the  occasion 
of  a visit  of  a party  of  about  one  hundred  and  eighty 
gentlemen,  comprising  heads  of  public  offices  and 
boards,  chemists,  geologists,  engineers,  architects  and 
others,  to  the  new  works  of  the  Patent  Concrete  Stone 
Company,  at  East  Greenwich,  Mr.  Eansome  showed 
and  explained  the  whole  process  of  making  stone  from 
sand,  and  exhibited  some  hundreds  of  the  objects  and 
ornaments,  many  of  them  of  great  beauty,  already 
made  to  the  order  of  architects  and  builders  for  various 
new  buildings  in  England  and  abroad. 

“ The  sand,  a clean-grained,  slightly  brownish  sort, 
just  such  as  a dishonest  grocer  might  select  for  increas- 
ing the  gravity,  specific  or  otherwise,  of  his  sugar, 
comes  from  near  Maidstone.  There  is  no  end  to  the 
quantity  of  it,  and  we  believe  it  costs  less  than  three 
shillings  a ton  in  the  Thames.  There  are  flints  enough 
for  a hundred  years  to  come  brought  up  from  the 
chalk  pits  at  Charlton  ; and  the  caustic  soda  and  the 
chloride  of  calcium,  the  latter  a waste  product  of  the 
soda  manufacture,  are  bought  of  the  wholesale  chem- 
ists. The  silicate  of  soda  is  made  from  the  flints  and 
caustic  soda  as  follows  : The  flints  are  heaped  upon 

iron  gratings  within  a series  of  cylindrical  digesters, 
of  the  material,  size  and  form  of  small  steam-boilei*s. 
A solution  of  caustic  soda  is  then  added ; the  digester 


192 


ABTIFICIAL  STONE. 


is  then  closed  steam-tight,  and  the  contents  are  boiled 
by  steam  of  seventy  pounds  taken  from  a neighboring 
boiler  and  led  through  the  solution  in  a coil  of  iron 
pipes.  The  solution  of  caustic  soda  is  prepared  of  a 
specific  gravity  of  about  1.200.  The  fiints  are  dis- 
solved into  ‘ soluble  glass,’  and  are  drawn  off  in  that 
state  as  a clear  though  imperfectly  liquid  substance, 
which  is  afterwards  evaporated  to  a treacly  consistency 
and  color,  and  of  a specific  gravity  of  1.700. 

The  sand  is  completely  dried,  at  the  rate  of  two 
tons  an  hour,  within  a revolving  cylinder,  through 
which  hot  air  is  forced  by  a centrifugal  fan.  A small 
portion  of  finely  ground  carbonate  of  lime,  say  Kentish 
rag,  or  even  chalk,  is  mixed  with  the  sand,  the  more 
closely  to  fill  the  interstices;  and  each  bushel  of  the 
mixture  is  then  worked  up  in  a loam  mill  along  with 
a gallon  of  the  silicate  of  soda.  Thoroughly  mixed 
with  this  substance,  the  sand  has  a sticky  coherence, 
sufficient  to  enable  it  to  be  moulded  to  any  form,  and 
when  well  rammed,  to  retain  its  shape,  if  very  care- 
fully handled.  In  this  condition — moulded,  of  course, 
and  any  thing  that  can  be  done  in  founder’s  loam  may 
be  done  in  this  sand,  sticky  with  silicate  of  soda — in 
this  condition  it  is  ready  for  the  solution  of  chloride 
of  calcium.  The  instant  this  is  poured  upon  the 
moulded  sand,  induration  commences.  In  a minute 
or  so  little  lumps  of  sand,  so  slightly  stuck  together 
by  the  silicate  of  soda  that  they  could  hardly  be  kept 
from  falling  to  pieces  within  the  fingers,  were  solidi- 
fied into  pebbles  so  hard  that  they  might  be  thrown 
against  a wall  without  breaking,  and  only  a short 
further  saturation  was  necessary  to  indurate  them 
throughout.  In  other  words,  on  the  instant  of  con- 


ARTIFICIAL  STONE. 


193 


tact,  the  silicate  of  soda  and  the  chloride  of  calcium 
mutually  decompose  each  other  and  reunite  as  silicate 
of  lime  and  chloride  of  sodium,  the  former  practically 
indestructible  in  air,  the  latter,  common  salt,  perfectly 
deliquescent  and  removable  by  washing,  although  the 
stone,  after  the  washing,  is  impermeable  to  water. 
Plaster  of  Paris  does  not  set  quicker  than  silicate  of 
soda  and  chloride  of  calcium. 

‘‘  The  chloric  solution  is  first  ladled  upon  the 
moulded  sand,  and,  the  hardening  going  on,  the  ob- 
jects are  afterwards  immersed  in  the  solution  itself, 
wherein  large  pieces  are  left  for  several  hours,  the  solu- 
tion being  boiled  in  open  tanks  by  steam  led  through 
it  in  pipes.  This  expels  any  air  which  may  have 
lodged  in  the  stone,  and  possibly  heightens  the  energy 
of  union  with  the  silicate. 

“ After  this  the  stone  is  placed,  for  a longer  or 
shorter  time,  according  to  the  size  of  the  object,  under 
a shower  bath  of  cold  water.  This  is  not,  by  bathing, 
to  covert  it  into  Bath  stone,  although  were  the  Bath 
stone  a sandstone  instead*  of  an  oolitic  formation,  this 
name  would  do  as  well  as  any.  The  salt,  or  chloride  of 
sodium,  deposited  throughout  the  interstices,  is  sought 
out  and  washed  away,  in  brine,  by  the  water,  and 
were  it  not  that  a portion  of  undecomposed  chloride 
of  calcium  is  also  washed  out,  this  brine  might  be 
profitably  evaporated  for  common  salt.  Now,  this 
searching  out  of  the  salt  by  the  water  would  appear 
to  prove  that  the  stone  was  perfectly  permeable,  but, 
by  one  of  those  paradoxes  with  which  chemistry 
abounds,  the  stone,  when  once  freed  from  salt,  is 
almost  impermeable.  The  action  is  one  which,  if  it 
can  be  explained  at  all,  can  only  be  explained  as  one 


194: 


ARTIFICIAL  STONE. 


of  the  phenomena  of  dialysis,  as  experimentally  in- 
vestigated by  Professor  Graham.  There  is  no  doubt 
whatever  that  salt  has  been  deposited  everywhere 
throughout  the  stone,  no  doubt  that  it  is  afterwards 
completely  washed  out,  and  yet  the  stone  as  effectually 
resists  the  passage  of  water  afterwards  as  if  it  were 
granite  or  marble. 

‘‘  It  is  not  necessary  to  describe  the  variety  of  ob- 
jects that  may  be  made  in  the  new  stone.  It  is  prac- 
tically a fictile  manufacture,  although  not  indurated 
by  fire,  and,  unlike  fictile  goods,  having  no  shrinkage 
or  alteration  of  color  in  the  making.  Whatever  the 
required  size  of  the  finished  stone,  it  is  moulded  exactly 
to  that  size,  with  no  allowance  as  in  moulding  fire-clay 
goods  or  in  pattern  making  for  castings  in  iron.  The 
heaviest  blocks  for  works  of  stability,  and  the  most 
elaborately  ornamental  capitals,  tracery  or  copies  of 
statuary  maybe  made  with  almost  equal  facility.  For 
any  purpose  for  which  natural  stone  has  ever  been 
used  for  construction  or  architectural  ornament, <afhe 
artificial  stone  will  fitly  take  its  place.  Mr.  Fowler 
has  used  it  extensively  in  the  stations  of  the  Metro- 
politan Kailway ; Messrs.  Lucas  Brothers  have  used 
it  with  success  in  various  works  ; several  manufacturers 
at  Ipswich  and  elsewhere  have  the  bed-stones  of  their 
steam  engines,  steam  hammers,  oil  mills,  &c.,  formed 
of  the  new  stone.  Mr.  Kansome  has  moulded  a large 
number  of  Ionic  capitals  for  the  l!lew-Zealand  post- 
office,  and  still  more  richly  embellished  capitals, 
modelled  from  those  of  the  Erectheum  at  Athens,  for 
public  buildings  at  Calcutta,  besides  a great  amount 
of  decorative  work  for  English  architects.  We  under- 
stand that  some  thousands  of  Corinthian  capitals  of 


ARTIFICIAL  STONE. 


195 


this  stone  are  specified  for  the  new  St.  Thomas’  Hos- 
pital. 

“ While,  however,  the  new  stone  afibrds  every 
facility  for  ornamental  moulding,  we  consider  that  its 
more  important  purpose  is  as  a substitute  for  ordinary 
cut  building  stone,  and  for  that  employed  in  pilasters, 
window  dressings,  garden  balustrades,  &c.  It  is  truly 
the  stone  for  the  million,  as  well  as  for  the  mullion, 
and  ought  to  take  the  place  of  stucco  for  exterior  work 
in  our  town  houses.  We  have  not  heard  that  the 
workmen  have  set  their  faces  against  it,  although  an 
intimation  of  this  sort  would  not^surprise  us  ; but  we 
should  suppose  that  a proper  knowledge  of  its  advan- 
tages would  insure  its  general  adoption  in  spite  of  any 
possible  opposition  of  this  kind.  We  believe  it  to  be 
the  fact  that  builders  are  slow  to  move,  but  there 
are  always  exceptions,  and,  as  in  other  trades,  great 
improvements  like  this  will  make  way  against  all 
opposition.” 

The  extreme  hardness  of  the  silicious  cement  which 
binds  together  the  grains  which  compose  this  material, 
secures  it  from  the  rapid  disintegration  which  takes 
place  when  steel  tools  are  ground  on  the  best  grind- 
stones formed  from  natural  rock.  The  following 
interesting  notice  of  these  stones  is  derived  from  the 
same  source  to  which  we  are  indebted  for  the  fore- 
going description  : 

‘‘  The  success  which  has  attended  the  application  of 
Mr.  Kansome’s  beautiful  process  to  the  manufacture 
of  artificial  grindstones  has  been  so  marked,  that  there 
seems  little  doubt  that  the  use  of  natural  stones  for 
grinding  purposes  will  eventually  become  the  excep- 


196 


ARTIFICIAL  STONE, 


tion  instead  of  the  rule.  Amongst  other  firms,  Messrs. 
Bryan,  Donkin  & Co.,  the  well-known  engineers  of 
Bermondsey,  have  tried  experiments  which  very  de- 
cisively prove  the  advantages  of  the  artificial  over  the 
natural  stones.  Messrs.  Donkin  were  first  supplied 
with  a pair  of  Mr.  Ban  some’s  artificial  grindstones  in 
December  last,  and  early  in  the  present  year  they  care- 
fully tested  these  stones  and  compared  their  efficiency 
with  some  J^ewcastle  stones  at  their  works.  Both  the 
natural  and  artificial  stones  were  mounted  in  pairs  on 
Muir’s  plan — a system  in  which  the  peripheries  of  the 
two  stones  of  each  pair  rub  slightly  against  each  other, 
with  a view  of  causing  them  to  maintain  an  even  sur- 
face— and  the  two  sets  of  stones  were  tried  under 
precisely  the  same  circumstances,  except  that  the  New- 
castle stones  had  a surface  speed  more  than  twenty 
per  cent,  greater  than  that  of  the  others. 

“ The  trials  were  made  as  follows  : A bar  of  steel, 
three-fourths  of  an  inch  in  diameter,  was  placed  in  an 
iron  tube  containing  a spiral  spring,  and  the  combi- 
nation was  then  arranged  so  that  the  end  of  the  bar 
projecting  from  the  one  end  of  the  tube  barely  touched 
one  of  the  artificial  stones,  while  the  other  end  of  the 
tube  rested  against  a black  of  wood  fixed  to  the  grind- 
stone frame.  A piece  of  wood  of  known  thickness 
was  then  introduced  between  the  end  of  the  tube  and 
the  fixed  block,  and  the  spiral  spring,  being  thus  com- 
pressed, forced  the  piece  of  steel  against  the  grind- 
stone. The  same  bar  of  steel  was  afterwards  applied 
in  the  same  way,  and  under  precisely  the  same  pressure, 
to  the  Newcastle  stone,  and  the  time  occupied  in  both 
cases  in  grinding  away  a certain  weight  of  steel  from 
the  bar  were  accurately  noted. 


AKTIFIOIAL  STONE. 


197 


“ The  results  were,  that  a quarter  of  an  ounce  of 
steel  was  ground  from  the  bar  by  the  artificial  grind- 
stone in  sixteen  minutes^  while  to  remove  the  same 
quantity  by  the  Newcastle  stone  occupied  eleven 
hours;  and  this  notwithstanding  that  the  surface 
speed  of  the  latter  was,  as  we  have  stated,  more  than 
twenty  per  cent,  greater.  Taking  the  twenty  per 
cent,  greater  speed  of  the  Newcastle  stone  into  ac- 
count, it  will  be  seen  that  the  eleven  hours  run  by  it 
were  equal  to  thirteen  and  three-quarter  hours  at  the 
same  speed  as  the  artificial  stone,  and  the  proportional 
time  occupied  by  the  two  stones  were  thus  as  sixteen 
minutes  to  thirteen  and  three-quarter  hours,  or  as  one 
to  fifty-two,  nearly  ! 

“ Such  a result  as  this  is  something  more  than  re- 
markable, and  it  is  one  which  would  scarcely  have 
been  credited,  even  by  those  who  made  the  experi- 
ments, if  it  had  not  been  fully  corroborated  by  subse- 
quent experience  in  the  working  of  the  artificial 
grindstones.  Since  the  experiments  above  described 
were  tried,  Messrs.  Donkin  have  set  another  pair  of 
the  artificial  stones  to  work,  and  these,  which  are  now 
in  regular  use,  have  given  even  more  satisfaction  than 
those  first  tried.  The  saving  in  time,  and  conse- 
quently in  labor,  efiected  by  the  use  of  the  artificial 
grindstones,  is,  in  fact,  so  great,  that  Messrs.  Donkin 
have  determined  to  use  these  stones  exclusively  in 
future  and  we  may  add,  that  the  artificial  stones  are 
so  much  preferred  by  the  workmen,  that  those  men, 
even,  who  are  employed  in  shops  at  some  distance 
from  that  in  which  the  stones  at  present  in  use  are 
situated,  prefer  taking  the  trouble  to  go  to  them  to 
using  the  Newcastle  stones  in  their  own  shops.  In 


198 


ARTIFICIAL  STONE. 


addition  to  their  great  efficiency,  the  artificial  grind- 
stones possess  the  advantages  of  being  able  to  be 
manufactured  of  any  size,  and  of  any  degree  of  coarse- 
ness of  grain,  and  they  can  thus  be  specially  adapted 
to  any  particular  class  of  work,  while^  the  process  of 
their  manufacture  insures  their  being  of  uniform 
texture  throughout,  and  free  from  the  flaws  and  hard 
and  soft  places  found  in  natural  stones.  Altogether, 
we  believe  that  the  general  adoption  of  the  artiflcial 
grindstones  is  merely  a matter  of  time.” 


CONCLUDING  REMARKS  ON  SOLUBLE  GLASS. 


It  has  been  stated  that  Liebig  and  Kuhlmann  recom- 
mend the  substitution  of  infusorial  earth  to  sand,  which 
is  a silicious  stone,  and  is  entirely  composed  of  millions 
of  the  remains  of  organic  beings,  called  diatoms,  which 
are  mostly  unicellular  plants,  and  have  a silicious 
shell,  and  pass  under  the  name  of  infusorial  earth  or 
tripoli,  or  mountain  meal,  and  has  generally  been  used 
for  polishing  stones  and  metals.  This  infusorial  earth 
was  first  brought  from  Tripoli,  but  abounds  in  many 
localities  in  North  Wales  ; in  Bohemia,  where 
are  beds  of  fourteen  feet  in  thickness ; in  Planitz,  in 
Saxony,  and  in  the  United  States,  there  are  many  places 
abounding  in  dried  up  lakes  and  rivers  from  the  fresh 
water  tertiary.  In  Virginia,  near  Bichmond,  there  is 
a bed  of  thirty  feet  in  thickness,  belonging  to  the 
eocene  period,  and  extending  from  Herring  Bay,  on 
the  Chesapeake,  Maryland,  to  Petersburg,  Virginia. 
At  Monterey,  California,  there  is  a bed  of  fifty  feet  in 
thickness  ; also  in  Barbadoes.  These  organic  beings 
are  extremely  minute ; the  Bilin  Tripoli  is  said  to 
contain  forty-one  millions  of  individuals  in  every  cubic 
inch,  which  weighs  about  220  grains.  The  fresh  water 
infusorial  earth  occurs  bountifully  in  Connecticut, 
Massachusetts  and  New-Hampshire,  where  thousands 
of  tons  may  be  dug  out. 

Much  time  must  have  been  required  for  the  accu- 
mulation of  strata  in  which  countless  generations  of 


200 


SOLUBLE  GLASS. 


these  diatoms  have  contributed  their  remains,  and 
these  deposits  have  led  to  further  discoveries,  so  that 
many  materials  which  have  been  supposed  to  be  inor- 
ganic, have  been  found  to  be  composed  chiefly  of  micro- 
scopic organic  bodies.  As  a proof  may  serve — the  white 
chalk— every  minute  grain  of  which  abounds  with 
thousands  of  well  preserved  organic  bodies  ; and  the 
white  coatings  of  the  flints  are  often  accompanied  by 
innumerable  needle-shaped  speculse  of  sponges. 

Dust  showers,  which  have  been  known  to  travel  for 
long  distances,  have  been  known  to  consist  of  micro- 
scopic organisms,  and  almost  invisible  to  the  naked  eye. 
The  green  sand  of  New-Jersey,  which  belongs  to  the 
later  cretaceous  group,  and  contains  these  innumer- 
able organic  remains,  consists  of  50  per  cent,  silica, 
25  per  cent,  iron  peroxide,  10  per  cent,  alkalies  of 
potash  and  soda,  10  per  cent,  water,  and  a trace  of 
phosphate  of  lime,  belongs  to  the  cretaceous  formation, 
and  has  a thickness  of  500  feet,  and  extends  from  Staten 
Island  to  the  head  of  Delaware  Bay,  thence  across  to 
the  Chesapeake  and  so  on  to  the  South.  The  rich  guano 
deposits  of  South  Carolina  are  included  in  this  creta- 
ceous period. 

In  order  to  make  the  New- Jersey  green  sand  and 
the  other  infusorial  deposits  available  for  our  purpose, 
the  green  grains  have  to  be  separated  by  a sieve  from 
the  accompanying  marl;  thus  separated,  they  are 
treated  with  hydrochloric  acid,  and  after  that  washed 
frequently  with  water  and  dried.  These  sands  are 
boiled  for  a few  hours  with  caustic  lye  of  soda,  so  that 
120  pounds  of  the  clear  sand,  treated  with  a lye  con- 
taining 75  pounds  soda,  must  produce  a concentrated 
liquid  of  250  pounds,  nearly  40°  B. 


SOLUBLE  GLASS. 


201 


It  is  well  known  that  the  affinity  of  silica  for  alkali 
is  so  feeble  that  it  may  be  separated  from  this  base 
by  the  'weakest  acids,  even  carbonic  acid.  In  the  silici- 
fication  of  stone,  the  carbonic  acid  of  the  atmosphere 
will  set  the  silica  free  from  the  soluble  glass,  and  the 
silica  thus  separated  will  be  deposited  within  the 
pores  and  around  the  particles  of  stone  or  wood,  so  as 
to  produce  a perfect  silicification,  a protection  or  hard- 
ening of  the  stone,  and  prevention  of  decay  from  dry 
rot  and  from  destruction  by  fire.  The  points  of  con- 
tact of  these  particles  will  thus  be  enlarged,  and  a 
coat  of  glazing  of  insoluble  silica  will  be  formed  suffi- 
cient to  protect  those  substances  from  the  effects  of 
moisture.  Sandstones  have,  in  this  manner,  been 
fully  preserved.  But  whenever  carbonate  of  lime  or 
carbonate  of  magnesia  enters  ratably  into  the  compo- 
sition of  building  stone,  then  an  additional  chemical 
action,  also  sheltering  the  stone,  is  expected  to  take 
place  between  these  carbonates  and  the  soluble  glass. 
An  insoluble  salt  of  lime  may  be  produced,  just  as  it 
is  found  in  the  native  minerals,  the  dolomitic  and 
oolitic  building  stones. 

The  principle  of  hardening  cements,  mortar  and  ar- 
tificial stone,  so  as  to  render  them  impermeable  to 
water  and  atmospheric  agents,  is  based  upon  this  ex- 
pressed theory  ; this  has  been  carried  so  far  as  to  sub- 
stitute the  soluble  glass,  not  alone  rendering  mortars 
water-proof,  but  also  as  a size  in  whitewashing  and 
staining  walls.  The  formation  of  an  insoluble  cement  by 
means  of  the  soluble  glass,  whenever  the  carbonic  acid 
of  the  atmosphere  acts  on  this  substance,  or  whenever 
it  is  brought  in  contact  with  a lime-salt,  has  been  de- 
monstrated in  the  Stereochromic  Painting^  which  is 


202 


SOLUBLE  glass. 


equal  to  the  process  of  fresco  painting.  It  is  the  fol- 
lowing process : 

Clean  and  Washed  quarts  sand  is  mixed  with  the 
smallest  quantity  of  lime,  so  as  to  enable  the  plasterer 
to  place  it  on  the  wall.  The  surface  is  then  taken  off 
with  an  iron  scraper,  in  order  to  remove  the  layer 
formed  in  contact  with  the  atmosphere ; the  wall  is 
then  still  moist  during  this  operation,  but  is  never  al- 
lowed to  dry ; after  drying,  it  is  just  in  the  state  in 
which  it  could  be  rubbed  off  by  the  finger ; the  wall 
is  now  moistened  with  the  liquid  soluble  glass,  which 
must  be  the  compound  of  silicate  of  soda  and  potassa 
of  the  highest  specific  gravity,  which  operation  is  per- 
formed with  a brush.  It  is  after  a little  while  in  such 
a condition  to  be  capable  of  receiving  colors;  if  the 
wall  has  been  too  strongly  fixed,  the  surface  has  to  be 
removed  with  pumice,  and  to  be  fixed  again.  Ee- 
paired  in  this  manner,  the  wall  is  suffered  to  dry. 
Before  the  painter  begins,  he  moistens  the  part  on 
which  he  proposes  to  work  with  soft  water,  which  is 
squirted  on  by  a syringe.  As  soon  as  the  picture  is 
finished,  it  is  aspersed  over  with  the  soluble  glass  after 
the  wall  is  dry,  the  syringing  is  continued  as  long  as 
a wet  sponge  can  remove  any  of  the  tint.  An  efflores- 
cence of  soda  sometimes  appears  on  the  picture  soon 
after  its  completion  ; this  may  be  either  removed  by 
syringing  with  water,  or  may  be  left  to  the  action  of 
the  atmosphere.  Not  to  dwell  on  the  obvious  ad- 
vantages possessed  by  the  stereochrome  over  the  real 
fresco,  such  as  its  admitting  of  being  retouched,  and 
its  dispensing  with  joinings,  it  appears  that  damp 
and  atmospheric  infiuences,  notoriously  destructive  of 


SOLUBLE  GLASS. 


203 


real  fresco,  do  not  injure  pictures  executed  by  this 
process. 

The  decorations  of  historical  pictures,  the  dimen- 
sioDs  of  which  are  21  feet  in  height  and  24J  feet  in 
width,  single  colossal  figures,  friezes,  arabesques,  &c., 
these  pictures  have  all  the  brilliancy  and  vigor  of  oil 
paintings,  while  there  is  the  absence  of  that  dazzling 
confusion  which  new  oil  paintings  are  apt  to  present, 
unless  they  are  viewed  in  one  direction,  which  the 
spectator  has  to  seek  for.  Leaves,  or  terra  cotta,  have 
been  executed  from  a substance  consisting  in  75  parts 
clay  and  25  parts  soluble  glass.  The  exudation  dur- 
ing damp  weather  of  the  alkalies,  either  the  potassa  or 
soda,  has  always  been  a serious  inconvenience  ; by  a 
careful  washing  with  hydrofluoric  acid,  determine  a 
complete  insolubility.  The  silicious  colors  on  glass 
have  a certain  semi-transparency,  which  is  important 
to  preserve,  but  which  gradually  diminishes  by  the 
action  of  water.  Glass  painted  with  silicates  has  been 
subjected  to  boiling  in  water  without  the  colors  being 
detached.  These  tints  have  even  appeared  brighter 
wlien  seen  by  reflected  light ; but  if,  after  this  appa- 
rent improvement,  the  effect  is  examined  by  trans- 
parency, the  hues  are  found  to  have  become  duller, 
which  is  to  be  attributed  to  the  capacity  which  they 
had  acquired,  resulting  from  the  solution  of  a portion 
of  silicious  cement,  which  acts  on  these  colors  as  oil 
does  on  paper.  The  careful  employment  of  hydro- 
fluoric acid  gives  a complete  insolubility  to  paintings 
on  glass,  but  chloride  of  ammonium  slightly  diminishes 
the  transparenC3^ 

In  an  economical  point  of  view,  the  soluble  glass 
prepared  from  infusorial  earths  is  much  easier  ob- 


204 


SOLUBLE  GLASS. 


tained,  and  leaves  less  residue  than  that  prepared  from 
sand  ; moreover,  the  solution  bj  alkalies  may  be  made 
in  a highly  concentrated  state  in  the  first  operation, 
so  as  to  produce  a neutral  jelly,  and  suitable  for  the 
manufacture  of  soap  and  adhesive  mucilage,  while 
that  prepared  from  sand  can,  at  the  first  operation, 
only  be  brought  as  high  as  25°  B.,  and  requires  another 
tedious  operation  of  concentration  to  the  proper 
strength  ; and  if  the  liquid  is  intended  for  certain  pur^ 
poses,  the  prevailing  alkali  requires  a neutralization 
by  hydrochloric  acid. 

We  may  safely  bespeak  for  the  abundant  supply  of 
infusorial  earths  a bright  future  in  the  manufacture 
of  all-alkaline  silicates. 


THE  ART  OF  GLASS  MAKING. 


Aaiong  all  the  discoveries  relating  to  the  arts,  none 
exceed  in  importance  and  nsefnlness  to  mankind,  the 
art  of  glass  making.  Glass  is  a chemical  combination 
of  sand  and  alkali,  or  alkaline  earth,  heated  to  fusion, 
and  • presenting  after  fusion  a transparent  and  hard 
body.  The  benefits  conferred  by  it  upon  all  classes 
of  human  society  have  been  immense ; the  spectacle, 
the  microscope,  the  telescope,  and  spectroscope,  have 
showered  incalculable  blessings  upon  the  world,  and 
there  are  probably  still  greater  discoveries  in  store  for 
us.  The  history  of  the  manufacture  of  glass  may  be 
traced  from  the  present  time  through  that  of  the  Ro- 
mans and  Phoenicians,  to  the  Egyptians,  some  of 
whose  productions  remain  to  this  age.  The  art  flour- 
ished in  Tyre,  in  Alexandria,  and  lastly  in  Rome  ; and 
after  being  depressed  for  some  ages,  again  revived 
under  the  Venetians,  who  transmitted  the  improved 
art  to  the  rest  of  the  nations  of  Europe.  Pliny  relates 
that  glass  was  first  discovered  by  accident  in  Syria,  at 
the  mouth  of  the  river  Belus,  by  certain  merchants 
driven  thither  by  the  fortune  of  the  sea,  and  obliged 
to  remain  there  and  dress  their  victuals  by  making  a 
fire  in  the  ground.  There  being  great  abundance  of 
the  herb  kali  in  that  vicinity,  the  ashes  of  the  plant, 
mixed  and  incorporated  with  the  sand,  formed  glass. 

Boerhave  says,  that  the  art  of  glass  making  is  of 
ancient  origin,  being  first  cultivated  in  Egypt,  while 

10 


206 


ART  OR  GLASS  MARING.- 


glass  was  rendered  malleable  in  the  age  of  Tiberins, 
and  is  now  manufactured  in  the  greatest  perfection. 
It  is  one  of  the  most  useful  arts  to  mankind  ^ for  by 
it,  in  conjunction  with  the  grinder’s  help,  we  obviate 
the  natural  infirmities  of  the  eye.  Without  it,  old 
people,  and  those  whose  optic  nerves  are  affected, 
would  be  debarred  the  knowledge  of  reading  letters 
or  books,  and  would  be  unable  to  sit  within  doors,  or 
in  a coach  or  ship,  and  see  all  things  clearly  around 
them,  yet  without  being  exposed  to  the  scourging 
heat  or  freezing  cold,  or  being  annoyed  with  the  east 
wind,  or  the  ingress  of  extraneous  filth.  Pure  glass 
will  scarcely  receive  any  stain,  and  is  easily  cleansed 
again.  Although  the  essential  constituents  of  glass 
are  silex  and  alkali,  it  generally  contains  other  sub- 
stances, such  as  metallic  oxides,  which  are  designed 
to  modify  its  external  character  of  hardness,  fusibility, 
brilliancy,  color  and  transparency.  Many  kinds  of 
glass  contain  either  potash  or  soda ; the  first  is  not 
much  employed  by  the  manufacturers  of  common 
glass.  Some  kinds  contain  lime  and  oxide  of  lead  and 
alumina  and  oxide  of  iron  ; the  two  latter  are,  how- 
ever, mere  accidental  impurities. 

There  are  no  reliable  records  of  the  processes  em- 
ployed by  the  ancients  in  the  making  of  glass.  From 
the  time  when  Agricola,  in  1550,  described  this  art, 
the  general  arrangement  of  the  furnaces,  the  mode  of 
fabrication  and  the  nature  of  the  materials  employed, 
and  even  the  tools  used  in  the  glass-house,  have  under- 
gone no  material  changes  in  the  processes,  if  we  may 
except  a few  natural  substances,  such  as  cryolite, 
fluorspar  and  felspar,  all  three  of  which  have,  for  the 


THE  GLASS  HOtTSE. 


207 


last  two  or  three  years,  been  introduced  by  glass  makers, 
either  for  the  opaque  and  vitrified  glass,  Eeaumur’s 
glass,  or  for  assisting  in  the  fluxing  of  the  glass  mate- 
rials ; also  the  substitution  of  bicarbonate  of  soda  in 
place  of  soda  ash.  All  works  on  the  manufacture  of 
glass  are  usually  devoted  to  the  arrangement  and  con- 
struction of  the  furnaces  and  pots,  the  tools  employed 
by  the  workmen  and  the  dexterous  mechanical  opera- 
tions, by  which  the  soft  and  ductile  metal  is  shaped 
into  various  forms,  that  fit  it  for  domestic  use  and  the 
purposes  of  science  and  the  arts. 

The  glass-house,  in  which  the  processes  of  melting 
and  blowing  are  performed,  is  usually  built  in  the  form 
of  a truncated  cone,  open  at  the  top,  60  to  80  feet  in 
height,  and  40  to  50  feet  in  diameter  at  the  base.  In 
the  centre  of  the  area  is  situated  the  melting  furnace, 
capable  of  holding  from  five  to  ten  glass  pots,  or  cru- 
cibles, for  melting  the  materials.  The  grate  of  the 
furnace  is  nearly  on  a level  with  the  floor  of  the  glass- 
house ; the  ash-pit  or  cave  is  a subterranean  passage, 
extending  from  each  side  of  the  furnace  to  the  exterior 
of  the  building,  so  as  to  catch  the  wind  from  as  many 
aspects  as  possible.  The  particular  arrangement  of 
the  glass-house  and  the  construction  of  the  furnaces 
are  somewhat  varied  according  to  the  glass  prepared. 

The  plan  of  a flint  glass-house  furnace  is  made  to 
contain  ten  pots,  with  as  many  flues,  one  flue  being 
placed  between  every  two  pots,  and  immediately 
abreast  of  each  pot  and  between  two  flues  is  an  aper- 
ture, called  the  working-hole,  which  is  used  for  intro- 
ducing the  raw  materials  and  taking  out  the  glass  or 
metal.  The  coals  are  shoveled  through  a square  hole 
upon  the  grate  in  the  centre  of  the  furnace.  The  grate 


208 


AET  OF  GLASS  MAKING. 


bars  are  supported  by  two  strong  iron  sleepers,  and 
are  protected  froni  the  intense  heat  by  being  previ- 
ously covered  by  a layer  of  clinkers  or  potsherds ; but 
as  the  furnace  attains  its  maximum  heat,  sufficient 
clinkers  are  formed  to  serve  the  purpose.  All  around 
the  grate  room  a bank  is  raised  termed  the  ridge,  on 
which  the  pots  are  placed,  so  that  the  fire  lies,  as  it 
were,  below  the  bottom  of  the  pots  and  in  the  centre 
of  the  furnace.  The  sides  of  the  furnace  are  a little 
higher  than  the  top  of  the  pots,  and  the  arch  or  crown 
is  made  as  low  as  possible  to  be  consistent  with  dura- 
bility. The  ladle  for  taking  out  the  metal  and  the 
stirring  rod,  all  made  of  wrought  iron,  are  the  appen- 
dages of  the  pot.  The  following  are  the  dimensions 
of  a fiint  glass  melting  furnace  : 

A ten  pot  furnace  is  12  feet  7 inches  in  interior 
diameter,  (while  each  pot  is  36  inches  in  diameter,) 
including  the  fines ; the  height  to  the  inside  of  the 
dome  is  4-J  feet ; each  of  the  arches  is  3 feet  1 inch  by 
3 feet  S-J  inches,  to  the  highest  part.  The  fire  is  regu- 
lated by  the  stoker  or  tender,  who  can  raise  the  heat 
of  the  furnace  to  the  highest  pitch  by  opening  holes  at 
the  bottom  of  the  grate.  A ten  pot  furnace  consumes 
from  eighteen  to  twenty-four  tons  of  coal  per  week. 

The  prevailing  high  temperature  of  a furnace,  which 
is  about  20,000°  F.,  makes  the  construction  of  a melt- 
ing furnace  very  difficult,  in  wear  and  tear ; and  in 
cases  where  open  pots  are  employed,  the  difficulty  is 
materially  increased  by  the  volatility  of  the  alkalies, 
which  amounts  to  nearly  twenty-five  per  cent,  both 
pots  and  furnace  rods  becoming  worn  out  or  too  much 
corroded  for  use.  In  ordinary  cases,  three  years  is  the 
usual  duration  of  these  furnaces,  except  in  fiint  glass- 


VARIOUS  FURNACES. 


209 


houses,  where  they  last  longer,  from  the  lower  melting 
point  of  the  materials  and  the  peculiar  shape  of  the 
pots.  The  sides  of  the  furnace  are  constructed  of 
bricks  formed  in  moulds  made  for  that  purpose.  The 
best  lire  clay,  mixed  with  the  remains  of  old  pots 
coarsely  ground,  is  the  material  employed  for  making 
these  pots.  The  roof  is  generally  made  of  sandstone 
alone,  of  a coarse  grit  and  very  porous.  No  cement 
is  employed  in  the  arch ; the  expansion  of  the  stone 
and  the  partial  fusing  of  the  interior  surfaces  after- 
wards, bind  the  whole  sufficiently  well  together. 

The  crown  and  plate  glass  furnaces  are  similar  to 
the  flint ; they  are  placed  also  in  the  middle  of  the 
cone,  but  contain  only  from  four  to  six  pots,  each  of 
the  capacity  of  half  a ton  of  metal. 

In  crown  glass  furnaces  there  are  also  the  blowing 
furnaces,  the  bottoming  hole  and  the  flashing  furnace, 
besides  an  aperture  in  the  latter  termed  the  nose-hole. 

The  leer  or  annealing  oven  is  one  of  the  most  im- 
portant appendages 'of  every  glass-house  ; it  is  a l^w 
arch,  open  at  both  ends,  in  which  the  manufactured 
goods  are  allowed  to  cool  gradually. 

The  arch  is  usually  about  sixty  feet  in  length,  five 
feet  wide  and  not  more  than  from  one  to  two  feet  in 
height.  Adjoining  the  door  or  receiving  end  is  a 
small  furnace  on  eacli  side,  by  which  the  temperature 
at  that  end  is  maintained  just  short  of  a melting  heat ; 
but  as  there  is  no  other  heating  power,  the  arch  or 
oven  experiences  less  and  less  of  the  heat  as  the  dis- 
tance from  the  mouth  is  greater,  until,  at  the  remote 
or  discharging  extremity,  the  temperature  is  scarcely 
higher  than  that  of  the  atmosphere. 

There  are,  usually,  from  two  to  four  of  these  an- 


210 


ART  OF  GLASS  MAKING. 


nealing  arches  placed  side  by  side.  Along  the  floors 
of  each  is  a miniature  railway,  upon  which  two  rows 
of  iron  trays,  called  leer  ^ans^  travel  from  the  pot  to 
the  cooler  end,  where  they  are  taken  out.  The  pans 
are  moved  slowly  along  the  leer  by  means  of  an  end- 
less chain,  or  sometimes  they  are  gradually  pushed 
forward  by  the  trays  last  put  in.  The  fuel  employed 
is  coke,  which  imparts  the  most  regular  heat  for  anneal- 
ing, and  is  the  freest  from  smoke,  the  carbon  of  which, 
when  coal  is  used,  injures  the  color  of  the  glass. 
The  time  required  for  proper  annealing  varies  from 
six  to  sixty  hours,  the  weighty  articles  requiring  the 
most  heat  and  time.  The  hotter  the  goods  enter  the 
oven  the  better,  and  on  this  account  large  articles,  before 
being  introduced,  receive  a final  reheating  at  the  mouth 
of  an  empty  pot,  heated  by  beechwood,  and  called  the 
glory-hole.  Much  of  the  success  of  the  annealing  de- 
pends on  the  proper  direction  of  the  wind,  which 
ought  to  pass  over  the  fuel  of  the  leer  towards  the 
leer  chimney  at  the  cooler  end,  so  that  the  hot  air  may 
always  radiate  in  the  downward  current  upon  the 
goods.  When  an  upward  or  contrary  current  of  wind 
drives  back  the  heated  air  from  the  cool  or  chimney 
end  towards  the  fuel  at  the  upper  end,  where  it  comes 
in  contact  with  the  hot  articles  just  introduced,  great 
losses  from  breakage  often  occur. 

Kilns,  which  are  closed  at  the  further  end,  were 
formerly  in  general  use  for  annealing  goods  intended 
for  deep  cutting,  the  kilns,  when  filled,  being  carefully 
closed  up  along  with  the  burning  fuel.  The  time  re- 
quired for  cooling  in  this  case  was  usually  about  a 
week ; but  to  avoid  so  much  delay,  the  kilns  have 
been  superseded  by  the  use  of  iron  covers,  or  a bed- 


GLASS  CRUCIBLES. 


211 


ding  of  sand  in  leers,  and  by  lengthening  the  leer  fire- 
places, and  not -filling  the  pans  with  glass  too  quickly. 

The  pots  or  crucibles  in  which  the  vitrious  mixture 
is  melted,  require  every  care  to  be  taken  in  their  pre- 
paration. Those  used  for  bottle,  crown  and  plate 
glass,  have  the  form  of  a truncated  cone,  the  narrow 
end  being  the  base.  Their  depth  is  usually  four  feet 
six  inches,  their  diameter  at  top  from  four  feet  to  four 
feet  six  inches,  and  at  the  bottom  about  three  feet  four 
or  six  inches.  The  pots  for  flint  glass  are  hooded  or 
covered  at  the  top,  and  have  a mouth  like  a muffle 
in  front;. but  those  for  crown,  plate  and  bottle  glass 
are  open.  The  horseshoe  shaped  piece  of  fire  clay  is 
inserted  in  the  m.outh  during  the  melting,  to  diminish 
the  aperture. 

Fire  clay  is  the  material  of  which  the  glass  pots  are 
made,  and  it  must  be  as  pure  and  refractory  as  can  be 
obtained,  free  from  every  trace  of  zinc  in  any  state, 
and  sulphide  of  iron,  and  the  less  oxide  of  iron  the 
better.  The  kind  of  slate  clay  dug  out  of  the  coal 
formation  near  Stourbridge,  which  contains  very  little, 
if  any  thing,  besides  silicic  acid  and  alumina,  is  decided- 
ly preferred  to  all  other  compounds  found  anywhere. 
The  clay  is  mixed  with  varying  proportions  of  ^the 
remains  of  the  old  pots,  and  the  tem])ering  or  previous 
preparation  of  the  mixture,  and  requires  great  atten- 
tion. A certain  quantity  of  the  ground  materials, 
after  being  mixed  with  water,  is  stored  away  in  large 
wooden  bins  or  receptacles,  and  turned  over  from  time 
to  time,  during  which  a workman  treads  it  under  his 
naked  feet.  This  kneading  of  the  clay  renders  it  very 
uniform,  and  free  from  particles  of  air.  The  follow- 


212 


AET  OF  GLASS  MAKING. 


lowing  is  the  composition  of  some  of  the  clays  em- 
ployed : 


Silicic  Acid,....  68.05  63.70  64.10  63.99  61.79 


Alumina, 18.85  20.70  23.15  20.84  18.97 

Lime, 80  1.30  — .30  1.53 

Magnesia, ......  — .90  — — .91 

Iron, 5.10  1.00  1.85  .75  .17 

Water, 6.10  10.30  10.00  11.67  14.79 

Loss, ...  1.20  3.00  — 1.31  1.86 


But  the  most  suitable  clay  for  glass  pots  of  any 
description  are  thirteen  parts  of  crude  aluminous  clay, 
twelve  parts  calcined  silicious  clay,  and  three  parts  of 
remains  of  old  pots. 

The  addition  of  old  pots  assists  in  the  more  regular 
drying  of  the  pots,  and  rendering  the  whole  body 
more  porous,  and  less  liable  to  crack  by  heat.  When 
the  mass  has  been  kneaded  three  times  over,  until  it 
acquires  a pasty  mixture,  it  is  rolled  into  small  pieces 
about  the  size  of  a sausage,  and  then  wet  rolls  are 
placed  together  upon  a wooden  or  leaden  slab,  to  the 
thickness  of  four  inches,  to  form  the  bottom.  It  is 
tlien  turned  up  at  the  edges,  and  built  layer  above 
layer  in  successive  rings,  all  formed  by  the  eye  of  the 
workman  without  the  use  of  a mould.  When  the  pot 
has  been  finished,  the  sides  are  made  smooth  by  means 
of  small  wooden  scrapers. 

After  the  glass  pot  is  formed,  it  is  allowed  to  remain 
for  a considerable  time  in  an  apartment  heated  by  a 
flue  to  a little  above  the  ordinary  temperature,  say 
80°  Fahr.,  in  order  that  it  may  be  slowly  dried  in  an 
equal  manner  throughout  its  whole  thickness.  Two 


SETTING  THE  GLASS  POTS. 


213 


or  three  years  is  the  time  allowed  by  some  manufactu- 
rers for  the  gradual  desiccation. 

Before  the  pot  is  set  in  the  furnace,  it  must  be 
subjected  to  an  annealing  process,  which  consists  in 
gradually  increasing  its  temperature  during  several 
days  to  bright  redness ; this  is  usually  done  in  a re- 
verberatory constructed  for  the  purpose,  the  fire  in 
which  must  be  raised  very  slowly,  not  more  tlian  a 
shovelful  of  coal  being  introduced  at  a time,  and  that 
at  regular  intervals.  While  at  a bright  red,  or  even 
white  heat,  the  pot  is  quickly  transferred,  with  the 
assistance  of  adequate  machinery,  into  its  seat  in  the 
hot  furnace;  a part  of  the  face  must  be  pulled  down, 
to  allow  of  the  extraction  of  the  old  pot,  and  intro- 
duction of  the  new  one.  Before  the  pot  is  used  it  is 
glazed^  as  it  is  termed,  before  being  filled  with  materi- 
als, that  is,  some  cullet  or  old  glass  is  thrown  into  it 
and  spread  over  the  sides  in  a molten  state  ; this  pene- 
trates to  the  depth  of  a few  lines  into  the  substance  of 
the  pot,  and  forms  a hard  difiiculty^ — fusible  enamel — 
which  protects  the  pot  from  further  action  of  the  sub- 
stances added. 

The  setting  of  a pot  is  a very  arduous  undertaking, 
and  some  dangers  attend  it,  on  account  of  the  dense 
heat  to  which  the  workmen  are  exposed ; it  is  gene- 
rally done  by  the  glass-house  crew,  and  is  done  at  the 
end  of  the  week,  when  the  work  of  the  glass-house  is 
slackened.  As  a test  of  the  soundness  of  the  pot, 
throw  a smalHump  of  coal  against  its  side ; if,  when 
struck,  it  rings  well,  its  future  is  promising ; but  if  it 
returns  a dull  sound,  it  will  probably  be  short-lived 
in  the  furnace.  The  average  duration  of  the  pots 
when  thus  fixed  is  about  seven  weeks ; some  attain 

10* 


214 


ART  OF  GLASS  MAKING. 


the  age  of  ten  or  twelve,  while  others  may  terminate 
their  existence  prematurely,  either  from  defective 
construction,  or  from  bad  treatment,  such  as  if  ex- 
posed to  a cold  air  in  the  furnace,  etc.  etc. 

The  Crude  Materials  for  Glass  Making. 

For  the  purpose  of  manufacturing  the  best  quality 
of  glass,  the  materials  composing  it  ought  to  be  per- 
fectly pure ; but  it  is  quite  impossible  to  obtain  on  a 
large  scale  or  prepare  the  ingredients  in  a state  of 
chemical  purity.  It  is  well  known  that  true  glasses 
are  practically  composed  of  silica  or  silicic  acid,  in  com- 
bination with  at  least  two  alkaline  bases  or  earths,  and 
sometimes  oxide  of  lead,  zinc  and  other  metals. 

Silex  is  the  principal  ingredient,  and  is  very  abun- 
dant in  nature,  forming  a principal  constituent  in  rocks 
and  stones,  and  existing  in  a free  and  almost  pure 
state  in  flint,  agate,  chalcedony,  rock  crystal  and 
quartz ; the  two  latter  are  in  the  purest  form.  Flint 
glass  obtained  its  name  originally  on  account  of  flint 
being  formerly  used  for  the  manufacture  of  glass ; but 
sand  is  now  employed  as  the  most  general  and  eco- 
nomical source  of  silica,  rendering  the  process  of  grind- 
ing unnecessary. 

At  the  same  time,  the  great  variations  in  the  purity 
of  this  material  render  requisite  a careful  selection 
for  the  different  kinds  of  glass,  and  the  manufacturer 
must  choose  such  as  the  microscope  and  analysis 
show  to  be  most  suitable  for  his_ purpose.  The  Eng- 
lish sands  of  fixed  quality  are  brought  from  Alum 
Bay,  on  the  Isle  of  Wight,  or  Lynn,  on  the  coast  of 
Norfolk.  The  French  obtain  a very  superior  sand 


GLASS  MATERIALS. 


215 


from  the  forest  of  Fontainbleau,  near  Paris;  in  this 
country  the  best  sand  is  procured  from  Berkshire 
County,  in  Massachusetts,  and  from  several  sand 
banks  on  the  Mississippi  River ; but  by  far  the  largest 
quantity  is  brought  from  Maurice  River,  in  New- 
Jersey,  and  also  from  the  Florida  coast. 

The  sand  being  always  more  or  less  impure  when 
brought  to  the  glass-works,  is  conveyed  to  an  upper 
room  and  thrown  into  a trough  of  water,  where  it  is 
carefully  washed  ; it  is  then  placed  in  a trough  over 
an  oven,  and  when  partially  dried  passes  through  holes 
into  the  oven  ; when  quite  dry,  it  leaves  the  oven  in 
the  state  of  fine  glittering  white  particles,  like  pow- 
dered quartz  ; this  preparation  is  not  required  for 
green  and  bottle  glass,  only  for  the  finer  qualities. 
The  alkalies,  potassa  and  soda,  are  now  employed  in 
their  purified  state,  although  formerly  crude  potashes 
from  wood  ashes,  and  crude  soda  from  Barilla,  pro- 
duced from  the  incineration  of  kelp,  have  always  been 
used  until  the  last  thirty  years,  and  which  produced 
very  variable  and  often  most  inferior  quality  of  glass. 

Le  Blanc’s  discovery  in  1792  of  the  conversion  of 
common  salt  into  carbonate  of  soda,  effected  a revolu- 
tion in  glass  making.  The  general  introduction  of  the 
carbonate  of  soda  in  England  dates  since  1831. 

It  is,  however,  noticeable,  that  sulphate  of  soda  has 
for  a long  while  been  used  in  glass  making,  and  rock 
salt  is  still  in  vogue  in  that  country;  the  Newcastle 
black  bottles  are  to  this  day  made  from  common  rock 
salt  and  the  sand  from  the  bed  of  the  river,  with  tlie 
carbonate  of  lime  of  the  soap  works,  and  the  tank 
waste  of  the  alkali  makers.  The  better  classes  of 


216 


ART  OF  GLASS  MAKING. 


glass  are  now  manufactured  from  the  purified  sand 
and  alkalies. 

Lime  forms  an  important  constituent  in  flint  glass  ; 
is  used  either  as  carbonate,  slaked  or  burnt ; but  such 
lime  which  contains  protocarbonate  of  iron  is  exclu- 
ded from  the  mixture  for  white  glass.  The  action  of 
lime  is  to  render  the  alkaline  silicates  insoluble,  and 
when  rightly  balanced  by  the  other  ingredients,  it  pro- 
motes the  fusion  of  the  whole  and  improves  the 
quality,  but  when  added  in  excess,  the  glass  becomes 
hard  and  difficult  to  work,  and  subject  to  devitrifica- 
tion. 

Lead  is  the  next  substance  in  point  of  importance, 
forming  the  distinguishing  ingredient  in  crystal  or 
common  flint  glass,  optical  glass  and  strass.  These 
glasses  are  fused  from  either  litharge  or  red  lead,  the 
latter  being  preferred  for  several  reasons ; it  is  finer 
in  a state  of  division — an  impalpable  powder;  and  be- 
cause it  is  decomposed  in  the  glass  pot  into  ordinary 
protoxide  of  lead  and  oxygen,  which  latter  assists  in 
the  oxydation  and  removal  of  many  impurities,  such  as 
charcoal,  &c.  An  excess  of  lead  acts  inj  uriously  upon 
the  melting  vessels,  and  besides  inducing  too  great 
softness  in  the  glass,  gives  it  a yellow  tinge.  There 
is,  however,  no  danger  of  an  excess  of  red  lead  being 
used  by  our  glass  makers,  who  have  an  eye  to  econ- 
omy, brought  about  by  the  great  competition  of  the 
glass  makers  in  the  various  sections  of  the  United 
States. 

Ba/ryta^  as  a sulphate  or  heavy  spar,  is  sometimes 
added  to  the  constituents  of  common  bottle  glass,  to 
render  it  more  easy  of  fusion. 

Alumina^  which  is  always  an  undesirable  ingredi- 


GLASS  MATEEIALS. 


217 


ent,  and  is  seldom  purposely  introduced  into  glass,  but 
is  always  accidentally  present  from  the  action  of  the 
materials  upon  the  clay  of  the  pots  ; it  renders  the 
glass  more  liable  to  devitrification,  for  it  increases  the 
number  of  silicates  and  more  compounded,  which,  as 
it  is  known,  makes  any  glass,  such  as  bottle  glass, 
easily  devitrified. 

Iron  is  an  unwelcome  element  in  glass,  but  is  ah 
ways  present  in  the  sand,  also  in  the  sulphate  of  soda, 
in  the  chalk,  partly  in  the  state  of  protoxide,  which, 
however,  is  removed  by  chemicals. 

Arsenic, — A little  arsenic  promotes  the  decomposi- 
tion of  the  other  ingredients,  and  tends  to  dissipate 
carbonaceous  impurities  not  otherwise  disposed  of, 
but  in  excess  it  produces  a milkiness  in  the  glass,  which 
increases  in  tensity  with  the  time. 

Borax  and  Boracic  Acid^  as  also  the  borate  of  lime, 
called  hayesine,  from  Peru,  are,  like  the  Chili  salt- 
petre, very  useful  and  powerful  agents  for  accelera- 
ting the  fusing  of  the  materials. 

Fluorspar  is  now  much  in  use,  and  were  it  not 
that  fluorspar  acts  too  detrimental  upon  the  pots,  and 
causing  the  metal  to  run  through  them,  it  would  be 
the  best  material  and  the  most  economical  in  glass 
making. 

Felspar  gives  a good  body  to  glass,  and  this,  wfith 
bone  ashes  and  silex,  makes  a milky  glass. 

Bone  Ashes  are  likewise  much  employed  for  pro- 
ducing a white  opalescent  glass. 

Green  Sand,  from  the  cretaceous  formation,  contain- 
ing the  infusorial  deposits  of  silicious  shells,  called  di- 
atoms, may  be  substituted  for  sand  or  silex  in  some 
glass  varieties. 


218 


ART  OF  GLASS  MAKING. 


Gullet^  a quantity  of  waste  glass,  which  is  abund- 
antly produced  in  every  manufactory  of  glass,  and 
wdiich  is  more  fusible  than  the  raw  materials,  facili- 
tates the  melting.  The  cullet  from  the  glass-house, 
and  that  collected  in  the  neighborhood,  are  carefully 
sorted,  cleaned,  ground  and  incorporated  with  the 
mixture  for  similar  kinds  of  glass.  Care  must,  how- 
ever, be  taken  that  no  inferior  kind  of  cullet  is  also 
mixed  with  the  ingredients  for  finer  glass.  Cullet  set 
alone  excites  fusion,  but  materially  aids  the  union  of 
the  bases  with  the  silicic  acid. 

Decoloring  Materials. — Every  description  of  glass 
has  a tendency  to  color,  which  is  more  or  less  de- 
veloped, even  when  proper  proportions  and  the  purest 
materials  for  the  mixture  have  been  employed;  and  as 
any  tinge  is  considered  a defect  in  white  glass,  or  that 
which  is  employed  for  windows,  and  particularly  in 
the  finer  kinds  of  glass,  certain  materials  are  employed 
with  the  special  object  of  counteracting  it.  To  this 
class  of  substances  belong  peroxide  of  manganese,  ar- 
senic and  nitrate  of  potassa.  The  accidental  elements 
which  usually  color  the  glass  are  iron  and  carbon,  or 
carbonaceous  matter,  and  in  all  cases  the  substances 
just  mentioned  are  employed  to  neutralize  or  counter- 
act them  by  means  of  oxydation. 

If  particles  of  carbon,  as  soot,  from  the  flame  or  Are, 
become  mixed  and  surrounded  with  the  melted  glass, 
these,  by  their  exclusion  from  the  access  of  air,  are 
prevented  from  burning,  and  a brown  or  nearly  black 
color  is  produced,  which  is  removed  by  the  conversion 
of  the  carbon  into  carbonic  oxide  through  the  influ- 
ence of  the  oxydizing  or  decoloring  material.  The 
manner  in  which  manganese  acts  on  the  protoxide  of 


COLORING  AND  DECOLORING  MATERIALS.  219 

iron  is  similar  to  its  action  on  carbonaceous  matters, 
which  are  thus  removed  in  gaseous  form  from  the 
melted  mass.  A few  ounces  of  the  peroxide  of  man- 
ganese are, ‘therefore,  usually  added  to  the  materials 
for  making  flint  glass,  wliich  is  always  required  in  a 
state  of  great  purity,  and  from  the  cleansing  action  of 
this  material,  it  has  received  the  familiar  title  of  glass- 
makers^  soap.  It  must,  however,  be  used  sparingly, 
for  an  excess  of  it  produces  a compound  of  silicic  acid 
with  sesquioxide  of  manganese,  which  comm  unigates 
a lilac  or  amethystine  color  to  the  glass.  The  ap- 
proved remedy  for  this,  when  the  error  has  been  com- 
mitted, is  to  stir  up  the  colored  mass  with  a wooden 
pole,  which  reduces  the  sesquioxide  to  the  protoxide, 
and  the  lilac  color  disappears.  Some  manufacturers 
use  manganese  on  account  of  the  reddish  tinge  it  im- 
parts to  glass,  expressly  to  disguise  the  bad  green  or 
yellow  colors  produced  by  the  other  materials.  In 
this  case  two  tinged  glasses  are  formed,  which  ma|k  6 
each  other’s  defects,  the  green  and  red  rays  combining 
together  as  supplementary  colors  to  transmit  white 
light.  In  fact,  in  plate  glass  for  flne  windows  a slight 
excess  of  manganese  is  sometimes  allowed,  expressly 
to  produce  an  amethystine  tint,  which  improves  the 
complexion  of  persons  who  receive  the  light  of  day 
through  the  window. 

Smalt,  a blue  glass,  is  sometimes  used  like  manga- 
nese, to  rnai^k  the  bad  colors  produced  by  the  other 
materials.  Properly  speaking,  however,  decoloring 
agents  are  those  which  act  by  oxydizing  the  carbon  or 
the  protoxide  of  iron,  and  thereby  actually  expelling 
the  lime.  In  this  way  nitrate  of  potassa  reacts  before 
the  glass  enters  into  perfect  fusion  ; arsenious  acid. 


220 


ART  OF  GLASS  MAKING. 


arsenic  acid  and  their  salts  exert  their  action  at  a 
temperature  above  the  fusing  point,  and  are  volatilized. 

Felsjpar  has  been  recommended  many  years  ago,  on 
account  of  its  ready  vitrification,  as  a go5d  material 
for  window  glass,  and  the  following  mixture  was  said 
to  be  proper,  viz. ; 

2 parts  of  felspar, 

2 “ sand, 

1 “ chalk, 

whicii,  however,  was  difficult  to  melt  and  prone  to 
devitrify. 

Another  mixture  has  been  proposed,  to  consist  of 
100  parts  felspar, 

100  clay, 

80  quicklime, 

which  mixture  produces  a bottle  glass,  provided  the 
clay  is  free  from  iron.  At  the  present  day  felspar  is 
used  in  connection  with  sand  and  fluorspar,  and  lime 
and  bone  ashes  are  added  by  some  manufacturers  for 
producing  a milk-white,  semi-transparent  enamel  glass. 

Glass  from  YolcaniG  Products. — Certain  lavas, 
pumices,  pitchstone,  obsidian  and  similar  products, 
approach  so  closely  to  bottle  glass  in  their  composition, 
that  there  is  no  doubt  but  what  they  will  be  turned  to 
account. 

Of  pumice  stone,  forge  scorise,  chalk  and  a little 
soda,  in  proper  proportions,  bottle  glass  must  be  made. 
Basalt  would  require  the  addition  of  chalk  and  soda. 
Lava  has  been  melted  without  the  addition  of  other 
ingredients,  and  produced  a fair  bottle  glass. 

The  Fuel. — In  England,  coal  was  formerly  em- 
ployed exclusively  in  the  manufacture  of  glass,  but  it 
has  been  found  of  late  that  oven-lurnt  cohe  is  much 


PREPARATION  OF  MATERIALS. 


221 


better  adapted  for  the  finer  glasses,  as  it  produces  less 
smoke  and  soot.  Some  glass-houses  have  all  the  re- 
quisite accommodations  for  making  coke.  In  France, 
both  coal  and  coke  are  used,  as  also  wood ; the  latter 
produces,  however,  less  heat  than  coal,  and  it  would 
require  a longer  time  to  fuse  the  metal.  In  Germany, 
wood,  and  also  peat,  is  generally  employed,  and  it 
may  be  safely  recommended  to  our  American  glass 
manufacturers  to  employ  peat  in  tlieir  furnaces  for 
obvious  advantages;  it  makes  no  smoke,  gives  less 
ash,  burns  with  a bright  flame,  gives  much  heat,  and 
is  economical,  and  can  be  had  in  the  United  States  in 
large  supplies. 

Prejparation  of 'the  Malerials. — A great  saving  of 
time  and  fuel  is  efiected  by  carefully  grinding  and 
intimately  mixing  the  materials  previous  to  the 
melting  ; for  this  purpose  edge-stones  and  coarse  sieves 
are  essential  in  a glass-house.  The  mixing  and*sifting 
has  hitherto  been  performed  with  the  hand,  and  very 
imperfectly.  A mixing  apparatus,  especially  intended 
for  crown  glass,  has  been  contrived ; it  is  made  entirely 
of  wood,  and  consists  of  a semi- cylindrical  chamber, 
with  an  opening  at  tlie  top  for  introducing  the  ma- 
terials, and  another  in  the  semi-circular  bottom, 
through  which  they  are  removed,  a cylinder  in  which 
a number  of  oblique  beaters  are  fixed,  and  the  whole 
made  to  revolve  by  a handle  or  a shaft  of  a steam- 
engine.  Also,  a simple  revolving  wooden  board, 
similar  to  those  employed  in  the  powder  factories, 
answers  all  its  purposes. 

The  composition  when  mixed  is  termed/’W^/  the 
great  advantage  of  fritting  or  stirring  the  materials 
together  is  in  the  partial  union  which  it  effected  be- 


222 


AElfOF  GLASS  MAKING. 


tween  the  silicic  acid  and  the  bases,  so  that  the  latter 
were  not  volatilized  in  the  furnace  previous  to  the 
formation  of  the  glass,  and  the  ppts  and  sides  of  the 
furnace  were  consequently  less  exposed  to  the  inju- 
rious action  of  these  vapors. 

Melting. — The  raw  materials,  consisting  essentially 
of  sand  and  silica  as  the  base  and  alkali  as  the  flux  or 
solvent,  having  been  thoroughly  incorporated  with  a 
suitable  proportion  of  cullet  or  broken  glass  of  the 
same  kind,  are  introduced  by  means  of  a clean  iron 
shovel  into  the  melting  pot,  which  has  been  pre- 
viously raised  to  white  heat.  But  the  whole  of  the 
mixture  is  not  introduced  at  once,  for  the  mass  of  glass 
which  a pot  will  hold  occupies  before  fusion  in  the 
state  of  frit  just  twice  the  space  of  the  melted  glass  ; 
not  more  than  one-third  of  the  mixture  is  put  in  flrst ; 
the  temperature  is  then  raised  to  the  maximum,  and 
as  the  mass  subsides  by  the  melting,  a fresh  quantity 
is  introduced,  until  the  pot  is  filled  with  melted  glass. 
During  the  whole  period  of  the  melting  or  found, 
the  stokers  or  teazers  keep  the*  furnace  well  supplied 
with  fuel,  so  as  to  prevent  any  portion  of  the  grates 
becoming  uncovered,  in  which  case  a rush  of  cold  air 
from  below  might  split  some  of  the  pots.  j£In  order  to 
notice  the  progress  of  the  fusion,  proofs  or  drops  are 
from  time  to  time  taken  out  of  the  pots  by  means  of  a 
short  rod,  flattened  at  one  end,  and  examining  if  any 
undissolved  grains  of  sand  are  perceptible  on  re- 
frigeration, and  whether  the  mass  appears  uniform 
throughout ; for  as  long  as  carbonic  acid  is  evolved  in 
abundance,  or  during  the  boil,  the  mass  is  agitated  by 
the  escape  of  large  bubbles  of  gas,  which  is  most 
favorable  to  the  operation. 


FINING. 


223 


This  action  answers  the  purpose  of  stirring ; it 
mixes  the  compounds  of  variable  degrees  of  fusibility 
and  density,  which  are  first  produced,  with  each  other. 
At  the  close  of  the  melting  process,  the  contents  of 
the  pot  are  not  by  any  means  pure  or  equally  mixed. 
All  the  solid  matter  is  dissolved,  but  the  mass  of  glass 
is  full  of  small  vesicles  of  gas,  presents  a spongy  rather 
than  a dense  appearance,  and  is  not  yet  in  a fit  state 
for  working.  The  surface  is  also  covered  by  a layer 
of  so-called  glass  gall  or  sandiver^  a melted  mixture  of 
salts,  which  have  not  been  volatilized,  nor  combined 
with  silica  during  the  process  of  melting,  and  consist- 
ing chiefiy  of  chloride  of  potassium  or  sodium,  and 
sulphates,  which,  in  consequence  of  imperfect  vitrifi- 
cation, have  escaped  decomposition.  Whenever  glass 
gall  occurs  in  large  quantities,  it  is  removed  with 
ladles,  and  is  mostly  employed  in  chemical  manu- 
factories of  saltpetre  and  alum ; it  does  not  occur 
when  the  purified  materials  have  been  employed  ; and 
if  any  glass  gall  rises,  it  may  then  be  removed  by 
volatilization. 

Fining. — For  some  time  the  glass  does  not  become 
transparent,  the  opacity  being  due  to  bubbles  of  air 
or  gas,  and  to  the  lime  and  earthy  impurities,  which 
do  not  fuse.  The  object  of  fining,  which  is  the  last 
process  in  glass  making,  properly  so  called,  is  the  re- 
moval of  these  by  the  subsidence  of  the  heavier  par- 
ticles to  the  bottom  and  the  escape  of  gas  at  the  sur- 
face. For  this  purpose  the  glass  must  be  brought  to 
the  most  fluid  state  possible,  and  the  heat  is  there- 
fore raised  and  sustained  for  some  hours  at  the 
highest  point.  In  40  to  48  hours  after  charging  the 
vitrification  is  complete.  When  all  the  gas  bubbles 


224 


AKl’  OF  GLASS  MAKING. 


have  passed  off,  and  the  sandiver  has  become  trans- 
parent and  colorless,  the  temperature  of  the  pot  is 
lowered  by  diminishing  the  draught,  which  is  termed 
cold  covering^  while  the  first  heating  process,  just 
mentioned,  is  called  hot  covering. 

The  object  is  now  to  bring  the  glass  from  a state  of 
nearly  perfect  fiuidity,  in  which  it  could  not  be 
worked,  to  that  free  viscid  or  plastic  condition  neces- 
sary for  the  working.  For  this  purpose  the  bars  of 
the  furnace  are  plastered  up.  The  great  thickness  of 
the  walls  and  the  slow  combustion  of  the  fuel,  which 
is  supplied  in  moderate  quantities,  keep  the  furnace 
hot  enough  to  retain  the  glass  in  a workable  viscid 
state  during  the  period  in  which  the  glass  is  blown  or 
otherwise  shaped  into  the  required  forms. 

Faults  in  the  Glass. — l^otwithstanding  all  the  pre- 
cautions that  may  be  taken,  air  bubbles  frequently  re- 
main and  generally  exist  in  great  numbers,  when  the 
fining  process  has  been  obstructed  by  too  great 
difficulty  of  fusion  in  the  glass ; these  are  called 
misters^  hlihe  or  seed. 

There  are  some  other  accidents  to  which  the  glass 
is  liable,  such  as  the  threads  or  strings,  which  are  con- 
tracted during  the  blowing,  and  waves  and  striae 
arising  from  a want  of  homogeneity  in  the  vitrous 
mass ; the  latter  is  produced  when  the  density  of  the 
glass,  in  consequence  of  imperfect  fusion,  is  not  uni- 
form throughout,  and  all  the  parts,  though  equal  in 
transparency,  do  not  refract  the  light  equally,  and  con- 
sequently images  of  objects  seen  through  the  glass 
appear  out  of  plac^  or  distorted.  This  fault  is  very 
objectionable  in  plate  glass  for  mirrors  or  windows,  as 
well  as  in  crystal  or  fiint  glass  for  optical  purposes. 


FAULTS. 


225 


Waves  are  superficial  and  protuberant  striae,  which 
always  occur  when  the  glass  is  blown  too  cold. 

The  working  tools  in  the  glass-house  are  to  this  day 
the  same  as  have  been  described  by  Blancourt  in 
1699,  without  any  variation  ; such  as  the  tube,  which 
is  the  most  indispensable  instrument,  made  of  wrought 
iron,  from  four  to  five  feet  long,  one  inch  thick,  and 
about  one-quarter  inch  in  the  bore. 

It  is  provided  with  a bulb  on  each  end  ; one  serves 
as  a mouth-piece,  while  the  other  is  used  to  attach  the 
melted  glass  on  it ; the  upper  portion  is  surrounded 
with  a wooden  cover,  to  protect  the  hands  of  the  work- 
man from  the  heat  of  the  metal.  Another  solid  rod, 
called  the  pontil  or  jponty^  serves  to  receive  the  glass 
after  it  is  blown  on  this  pipe.  The  springtool  is  a 
species  of  tongs  for  laying  hold  of  half-formed  handles, 
and  for  seizing  the  glass  while  making.  The  pucellas 
are  prongs  resembling  the  cutting  part  of  shears,  but 
blunt,  and  are  used  for  rubbing  the  outside  of  solid 
or  hollow  glass,  and  pressing  it  into  a smaller  diameter, 
at  the  same  time  elongating  the  parts  by  rotation. 
The  lattledor  is  made  of  wood,  and  is  used  for  flatten- 
ing the  glass  when  necessary.  The  shears  are  strong 
scissors  for  cutting  and  shaping  the  edges  and  handles 
of  glass  vessels  while  in  a soft  state.  The  fovTc  is  em- 
ployed for  carrying  the  finished  articles  to  the  anneal- 
ing oven.  The  marver  is  an  iron  plate  or  slab  resting 
on  stone  or  wooden  supports,  and  having  a polished 
surface,  oi^ which  the  mass  of  glass  which  has  been 
gathered  at  the  end  of  the  blowing  tube  is  rolled  to 
give  it  a symmetrical  form  ; marver  is  derived  from 
the  French  word  mai'hre — marble. 

The  glass-maker’s  chair  is  the  last  utensil  used  in  the 


226 


ART  OF  GLASS  MAKING. 


glass-house  ; it  is  a hat  seat  of  wood,  about  ten  inches 
wide,  each  end  of  which  is  fixed  to  a frame  connected 
with  four  legs  and  two  inclined  arms,  upon  which  is 
screwed  an  edging  of  wrought  iron  for  rolling  the 
blowing  tube  with  the  hot  glass  backwards  and  for- 
wards with  the  left  hand,  while  the  required  form  is 
given  to  the  glass  with  the  pucellas  held  in  the 
right. 

Continual  rotation  of  the  melted  mass  is  the  princi- 
pal point  to  be  attended  to  in  most  of  the  glass-blower’s 
operations,  but  these  may  have  to  be  explained  when 
alluding  to  the  various  kinds  of  glass. 

The  manufacture  of  glass  is  divided  into  several 
classes  : 

A.  Window  glass,  which  includes, 

1.  Crown  glass. 

2.  Sheet  glass. 

3.  Brown  plate,  silvered  or  unsilvered. 

4.  Colored  sheet,  pot  metal  or  fiashed. 

B.  Painted  and  other  kinds  of  ornamental  window 
glass. 

C.  Cast  plate  glass. 

a.  Bough  plate. 

h.  Pressed  plate. 

c.  Boiled  plate. 

D.  Bottle  glass. 

1.  Ordinary  bottle  glass. 

2.  Moulded  bottle  glass. 

3.  Medicinal  bottles. 

4.  Tubing. 

E.  Glass  for  chemical  and  philosophical  purposes, 
retorts,  reservoirs,  large  water  pipes,  etc.,  etc. 


CLASSES  OP  GLASS. 


227 


F.  Flint  or  crystal  glass,  with  or  without  lead ; 
white,  colored,  ornamented,  for  table  ware,  etc. 

1.  Blown. 

2.  Moulded  and  pressed. 

3.  Cut  and  engraved. 

4.  Keticulated  and  spun  with  a variety  of  colors, 
incrusted,  flashed,  enameled  of  all  colors,  opalescent, 
imitation  of  alabaster,  gilt,  gelatinized,  silvered. 

5.  Glass  mosaic,  miliflori,  aventurine  and  Vene- 
tian glass  weights. 

6.  Beads,  and  imitation  of  pearls,  etc. 

7.  Chandeliers,  candlesticks  and  lamp  apparatus. 

G.  Optical  glass,  flint  and  crown. 

1.  Eough  disks  of  flint  and  crown,  to  make  lenses 
for  telescopes,  microscopes,  stereoscopes,  spectroscopes, 
daguerreotype  and  calotype,  apparatus. 

2.  Flint  and  crown,  blown,  or  cast  in  plates  for 
the  optician. 

3.  Fine  glass  for  microscopes. 

4.  Eefractive  apparatus,  prismatic  lenses  for  light- 
houses. 

The  above  classification  was  made  at  the  London 
universal  exhibition  of  1851.  Another  classification 
is  made  in  the  following  kinds,  according  to  their 
constituent  materials  : 

1.  The  soluble  glass,  silicate  of  soda  or  potash,  or 
both  alkalies  combined  with  silica. 

2.  Bohemian  glass,  a silicate  of  potash  and  lime. 

3.  Crown,  or  spread,  a silicate  of  soda'and  lime. 

4.  Plate,  a silicate  of  soda  and  lime  cast  into  plates. 

5.  Bottle,  a silicate  of  potassa,  lime,; alumina  and 
oxide  of  iron. 

6.  Crystal,  silicate  of  potash  and  oxide  of  lead,  j 


8 


ART  OF  GLASS  MAKING. 


7.  Flint  contains  more  lead  than  the  last. 

8.  Strass,  or  paste,  contains  still  more  lead  than 
flint. 

9.  Enameled  and  colored  glass,  from  all  the  above 
except  No.  1 and  No.  5. 

The  following  is,  with  some  modiflcations,  arranged 
by  Knapp,  beginning  with  the  coarser  or  common 
qualities,  and  rising  by  a natural  gradation  to  the 
finer  or  rarer  kinds  of  glass  : 

I.  Ordinary,  or  green  bottle  glass. 

II.  White  bottle  glass,  including  refractory  Bohe- 
mian and  pressed  crown  glass. 

III.  Window  glass,  or  English  crown,  of  sheet  or 
cylinder  glass. 

lY.  Plate  glass. 

Y.  Crystal,  or  common  flint  glass,  and  optical  flint 
glass. 

YL  Strass,  and  colored  or  stained  glass. 

YII.  Soluble  glass. 

I.  Green  Bottle  Glass. — The  materials  for  common 
glass  bottles  are  coarser  and  cheaper  than  for  any  other 
kinds  of  glass,  and  in  consequence  of  this  very  coarse- 
ness or  want  of  refining,  the  elements  which  enter 
into  its  composition  are  more  numerous,  consisting,  as 
stated,  of  silica,  lime,  potassa  or  soda,  oxides  of  iron 
and  manganese ; these  last  communicate  a color  to  the 
glass,  which  owes  at  the  same  time  its  characteristic 
hue  to  the  charcoal.  Indeed,  as  the  color  of  bottle 
glass  may  be  considered  as  essential  to  it,  or  at  least 
does  not  injure  its  sale  or  diminish  its  value  for  the 


GKEEN  BOTTLE  GLASS. 


229 


purposes  to  Ti’liicli  it  is  applied,  no  recoloring  materials 
are  used,  and  it  is  melted  in  open  pots,  even  wlien  coal 
is  used  as  fuel.  The  omission  of  decoloring  materials 
forms  the  distinguishing  feature  of  ordinary  bottle 
glass. 

The  primary  materials  of  the  manufacture  of  this 
kind  of  glass  are  yellow  or  ferruginous  sands,  residues 
* from  the  lyes  of  the  soap  and  soda  works,  lixiviated 
ashes,  common  ashes  and  clay.  The  colored  sands  are 
preferable  to  white  sand  for  bottle  glass,  the  oxide  of 
iron,  which  colors  them,  performing  a part  of  a flux  ; 
they  do  not  require  any  w'ashing  or  other  preparation  ; 
nevertheless,  any  coarse  foreign  substances,  such  as 
pyrites,  flints,  &c.,  are  separated  from  them  ; for  this 
purpose,  they  are  dried  and  passed  through  a sieve. 
The  clay  best  adapted  for  this  purpose  is  a yellow  marly 
earth,  a furnace  clay  containing  alumina,  silica,  car- 
bonate of  lime,  oxides  of  iron  and  manganese  ; it  has 
not  much  of  a binding  quality,  and  is  easily  reduced  to 
povrder  when  dry,  which  facilitates  the  mixture.  The 
ashes  are  generally  obtained  from  common  domestic 
flres,  and  are  sifted  and  dried  before  using. 

The  following  formula  is  used  in  France  for  ordi- 
nary French  bottle  glass  : 


Yarix,  (kelp,) 
Lixiviated  ashes. 
Fresh  ashes, 
Cla}q  containing 
iron. 

Broken  glass. 


30  to  40  lbs. ; sand,  100  lbs. 
160  to  ITO 
30  to  40  ‘‘ 

80  to  100  “ 

100  lbs. 


11 


230 


ART  OF  GLASS  MAKmG. 


The  English  bottle  glass  is  composed  of— 


Lixiviated  asheSj 
Kelp, 

Wood  ashes, 


Clay, 

Gullet, 


100  lbs. ; sand,  100  lbs, 
40  to  80 
30  to  40  “ 

80  to  100 
100  lbs. 


The  amount  of  cullet  is  not  particular ; it  is  increased 
for  the  first  and  second  melting  when  new  pots  are 
used  ; if  a very  argillaceous  sand  is  used,  it  is  neces- 
sary to  suppress  the  clay,  and  supply  lime  by  a suit- 
able addition  of  chalk.  Crude  soda  may  be  used. 

Champagne  and  soda-water  bottles: 

For  100  lbs.  sand,  add 


Felspar,  200  lbs. 

Lime,  20  “ 

Common  salt,  15  “ 

Iron  slag,  105 

For  ordinary  green  bottle  glass  : 

Sand,  100  lbs. 

Lime,  72  ‘‘ 

Lixiviated  wood  ashes,  200  “ 

Dark  green  bottle  glass  : 

Sand,  loo  lbs. 

Dry  glauber  salt,  20 

Soapboilers’ fiux,  18 

Lixiviated  ashes,  1 “ 

Glass  from  the  hearth,  32  “ 

Broken  glass,  179 

Basalt,  45  “ 


GREEN  BOTTLE  GLASS. 


231 


Hock  wine  bottles  : 

Sand, 

100  lbs. 

Claj, 

100  “ 

Sulphate  of  soda. 

50  “ 

Best  black  lead. 

25  “ 

The  colored  aerated  water  bottles  : 

To  100  lbs.  of  common  sand,  add 

Sulphate  of  soda, 

50  lbs. 

Lime, 

20  “ 

Felspar, 

50  “ 

Zafifre-, 

5 

The  cheapest  bottle  glass  is 

composed  of— 

Sand, 

200  lbs. 

Lime  or  chalk. 

100  “ 

Common  salt. 

25  ‘‘ 

Iron  slag, 

50 

The  melting  furnace  for  bottle  glass  contains  com- 
monly only  six  pots,  about  three  feet  in.  height  and 
nearly  the  same  in  diameter  ; they  are  filled  to  the  edges, 
and  when  the  matter  has  sunk  down  and  is  con- 
verted into  glass,  more  of  the  composition  is  put  into 
the  pots,  and  the  fire  is  urged  ; the  meltings  are  rapid, 
for  as  most  of  the  bottle  glass  compositions  furnish  but 
little  glass  gall,  no  time  is  lost  in  firing.  The  pro- 
cess lasts  from  seven  to  ei^ht  hours,  and  wdien  it  is 
concluded  the  fire  is  slackened,  that  the  glass  may 
thicken  to  the  point  suitable  for  working  it.  For  this 
purpose  the  fire-place  is  heaped  up  with  small  coal  ; 
draughts  are  intercepted  as  much  as  possible,  and  care 


232 


ART  OF  GLASS  MAKING. 


is  taken  not  to  touch  the  fire  during  the  working  of 
the  glass,  lest  the  combustion  should  be  re-excited. 

The  working  or  shaping  of  bottle  glass  is  very  sim- 
ple in  principle,  and  yet  the  operations  involved  are 
somewhat  complex  in  detail.  The  assistant  collects 
or  gathers  at  the  end  of  the  pipe  the  requisite  body  of 
glass,  and  passes  it  into  the  blower ; the  latter,  by  blow- 
ing and  constantly  turning  the  pipe,  gradually  forms 
the  body  of  the  bottle,  which  is  finished  in  a mould. 
While  the  bottle  is  in  the  mould,  the  workman  con- 
tinues to  blow  and  to  turn  ; he  then  raises  the  pipe,  and 
holding  the  bottle  in  a vertical  and  reversed  position, 
he  depresses  or  hollows  the  bottom  ; the  bottle  is  then 
cut  at  the  neck,  and  the  iron  rod,  the  ponty,  fixed  at 
the  opposite  end  of  it ; the  edge  of  the  neck  is  rounded, 
and  the  ring  or  cord  which  encircles  it  is  put  on  ; the 
ponty  then  passes  into  the  hands  of  the  assistant, 
whose  duty  it  is  to  carry  it  to  the.  annealing  furnace, 
and  he  then  detaches  it  from  the  rod  by  a slight  blow. 
Large  round  bottles  are  blown  without  the  use  of  a 
mould,  and  when  of  very  great  size,  like  the  carboys 
for  oil  of  vitriol,  the  aid  of  steam  is  called  in,  by 
spirting  about  an  ounce  of  water  into  the  interior  of 
the  tube,  and  holding  the  mouth  of.  the  pipe  with  the 
thumb. 

Bottles  in  the  shape  of  fiattened  globes  are  also 
made  without  any  mould  by  simple  blowing.  The 
preparation  of  the  mass  of  glass,  the  formation  of  the 
concave  bottom  and  of  the  neck  is  effected  with  ease 
by  an  expert  workman  ; the  swinging  motion  must 
not  be  continued  for  anj^  length  of  time.  In  blowing 
the  belly  of  the  bottle,  the  workman  stands  in  front 
of  a slanting  board,  and  presses  the  globe  as  it  is 


WniTE  BOTTLE  OR  CHEMICAL  GLASS. 


233 


gradually  formed  by  slow  blowing  against  the  board 
at  eveiy  half  revolution  of  the  pipe  ; the  flat  surfaces 
on  opposite  sides  are  thus  produced. 

Bottles  intended  to  resist  a high  pressure,  like  cham- 
pagne and  soda-water  bottles,  have  to  be  carefully 
handled,  for,  owing  to  internal  pressure,  may  easily 
crack  them,  and  occasion  great  loss  and  be  even  disas- 
trous. 

It  has^  been  ascertained  that  such  bottles  will  stand 
a pressure  of  twelve  atmospheres  ; and  various  ma- 
chines liave  been  invented  to  affect  the  test  by  forci- 
bly pumping  water  into  the  bottles  until  the  manom- 
eter is  of  the  sufficient  degree  of  force  used  in  this 
operation. 

The  mode  of  filling  and  annealing,  as  well  as  the 
form  of  the  bottles,  must  exercise  a great  influence, 
which  it  would  be  necessary  to  find  the  means  of  es- 
timating. 

II.  ^Vhite  Bottle  or  Cheinical  Glass. — Bottles  for 
medicinal  and  chemical  use,  and  tubing  of  a refractory 
condition.  This  is  composed  of  purer  materials  than 
the  green  decoloring  matters,  ajid  the  materials  as 
much  free  from  iron  and  alumina  as  possible,  and  the 
glass  is  subjected  to  a thorough  fining  process. 

Apothecaries'’  Phials : 


White  sand. 
Impure  potassa. 
Lime, 

Ashes, 

Manganese, 


100  lbs. 
' 30-35  “ 
17  “ 

110-120  “ 


5 “ 
25 


Gullet, 


234 


AKT  OF  GLASS  MAKING. 


Bohemian  Crystal.,  for  grinding  : 

Sand, 

100  lbs, 

Purified  potassa, 

60  ‘‘ 

Chalk, 

8 “ 

Broken  glass, 

40  “ 

Manganese, 

1 “ 

Semi-  White : 

Sand, 

100  lbs, 

Crude  soda,  containiug  lime. 

100  “ 

Cullet, 

100  “ 

Manganese, 

1 

Clear  White: 

White  sand, 

100  lbs. 

Calcined  potassa. 

65  “ 

Slaked  lime. 

6 ‘‘ 

White  cullet. 

100 

Manganese, 

5 “ 

White  Glass ^ for  chemical  purposes  : 

Sand,  . 100  lbs. 

Potassa,  41  ‘‘ 

.Lime,  17  “ 

Bohemian  Glass. — This  glass  is  particularly  valued 
for  its  refractory  nature,  freedom  of  color  and  great 
lightness ; tubing,  retorts,  &c.,  will  not  alone  re- 
sist high  heat,  but  also  sudden  changes  of  tempera- 
ture ; also  for  table  ware,  costly  windows  for  houses 
and  carriages,  for  covering  engravings,  and  in  general 
for  all  those  uses  which  require  the  glass  to  have  a 
considerable  thickness  without  coloration. 


CROWN  GLASS. 


235 


In  common  with  crown  glass,  it  is  also  peculiarly 
fit  for  optical  instruments,  in  which  it  is  employed  to 
achromatize  the  flint  glass. 

It  is  made  by  the  following  formula  : 

Quartz  in  powder,  or  fine  silicious 

sand,-coated  with  hydrochloric  acid,  100  110  120 

Purified  carbonate  of  potassa,  60  61  66 

Pure  carbonate  of  lime,  20  21  25 

By  analysis  of  the  old  manufactured  Bohemian 
glass,  was  found 


Bohemian  glass  is  a silicate  of  potassa  and  lime, 
with  a small  proportion  of  alumina,  magnesia  and 
other  ingredients. 

Crown  Glass. — It  is  likewise  a silicate  of  potassa 
and  lime,  and  the  English  crown  glass  contains  the 
soda  instead  of  the  potassa. 

The  analysis  of  a German  crown  glass  produced 


Silica, 

Alumina. 

Lime, 

Potassa, 


69.1 

9.6 

9.2 

11.8 


Silica, 


62.8 


Alumina,  ox.  iron  and  manga  , 2.6 


Lime, 

Potassa. 


12.5 

22.1 


The  beauty  and  value  of  this  glass  depends  upon 
its  absolute  lirapidness,  and  requires  the  most  careful 
selection  of  materials  for  the  mixture  and  the  pots, 


236 


AET  OF  GLASS  MAKING. 


and  protracted  and  assiduous  process  of  fining  are  re- 
quired. Soda  does  not  produce  as  colorless  a glass  as 
potassa,  nor  ought  it  to  contain  any  oxide  of  lead,  but 
requires  lime;  there  is  danger  of  devitrification  if 
potassa  is  employed,  and  very  good  reasons  are  known 
to  exist  why  lime  in  combination  with  potassa  ought 
to*  be  used. 

III.  Window  Glass, — The  glass,  which  has  long 
been  in  common  use  for  wfindow  panes,  is  that  which 
is  generally  known  as  English  crown  glass,  in  the 
manufacture  of  which  a large  globe  is  first  blown  at 
the  end  of  the  pipe,  and  is  converted  by  a rapid  rotary 
motion  into  a circular  plate  or  disc,  thickened  at  the 
centre.  Still  better,  the  present  method  is  to  form  a 
globe  into  a cylinder,  and  then,  after  cutting  it  up  in 
a direction  parallel  to  the  axis,  flattening  it  out  into  a 
broad  sheet ; from  this  fact  it  has  been  named  “ sheet 
glass.”  Plate  glass,  or  that  which  is  cast  into  sheets 
by  pouring  the  liquid  metal  on  a flat  surface,  is  now’ 
much  used  for  the  same  purpose,  as  for  window^s  of 
shops,  &c.  The  chief  demand  for  plate  glass  is  still 
for  mirrors.  The  English  crown  and  sheet  glass  are 
composed  of  precisely  the  same  materials,  and  difier 
only  in  the  mechanical  operations  by  which  they  are 
brought  into  form.  The  composition  of  the  English 
crowm  and  sheet  glass,  under  the''  name  of  window 
glass,  are  chiefly  silica,  soda  and  lime;  sometimes 
potassa  is  added  to  the  mixture.  Alumina,  oxides  of 
iron  and  manganese  are  also  found  in  wdndow  glass, 
either  by  accident  or  purposely  ; for  where  iron  is 
present  it  requires  the  addition  of  manganese  to  neu- 
tralize the  efiPects  of  iron  ; a little  arsenic  is  also  gene- 
rally added  to  promote  the  decomposition  of  the  other 


WINDOW  GLASS. 


237 


ingredients.  It  is,  however,  a well  ascertained  fact, 
that  no  two  manufacturers  use  the  same  materials, 
and  it  may  even  sometimes  be  necessary  to  vary  the 
proportions  of  the  composition,  on  account  of  the  melt- 
ing power  of  the  furnace. 

The  following  is  the  usual  composition  of  the  crown 
glass,  viz.  : 


Sand, 

500  and  518  lbs 

Chalk, 

151  and  146  “ 

Carbonate  of  soda. 

119  and  118  ‘‘ 

Sulphate 

n 

63  and  17 

Arsenic, 

2 and  2 

Cullet, 

448  and  448  “ 

The  French  crown  glass  consists  in — 


Sand, 

100 

lbs. 

Chalk, 

35 

to 

40 

lbs. 

Dry  carbonate  soda. 

28 

to 

35 

u 

Broken  glass. 

60 

to  180 

u 

Peroxide  manganese. 

25 

to 

35 

u 

Arsenic, 

20 

to 

30 

u 

The  three  following  formulae  for  crown  glass  : 


White  sand. 

100 

lbs. 

100 

lbs. 

100 

lbs. 

G-ood  potassa. 

65 

u 

0 

0 

u 

Good  soda. 

10 

u 

90 

a 

80 

a 

Lime,  slaked. 

6 

u 

0 

u 

8 

u 

Broken  glass. 

50 

(( 

100 

(( 

110 

(( 

Arsenic, 

1 

(( 

0 

u 

0 

ii, 

Oxide  of  manganese. 

i 

(( 

i 

u 

3 

a 

Carbonate  of  lime. 

0 

u 

5 

0 

Oxide  of  cobalt. 

0 

u 

0 

u 

u 

11^ 


238 


ART  OF  GLASS  MAKING. 


A beautiful  window  glass  is  obtained  bj  the  follow- 
ing formula : 

Sand,  100  lbs.  100  lbs. 

Dry  sulphate  of  soda,  44  “ 58  to  75  lbs. 

Charcoal  in  powder,  4 “ 4.5  to  5.5  “ 

Slaked  lime,  6 “ 13  to  15 

Broken  glass,  100  “ 100  lbs. 

The  manipulations  of  the  English  crown  glass  is  the 
following : 

The  metal  or  melted  glass  having  been  brought  by 
the  gradual  cooling  of  the  furnace  from  a state  of  com- 
plete fluidity  to  a consistence  capable  of  being  worked, 
the  gatherer  dips  the  end  of  his  pipe  or  hollow  rod  of 
iron  into  the  pot  inside  of  a ring,  which  is  kept  in 
the  furnace  floating  over  the  melting  mass,  and 
twirling  it  around  its  axis  to  equalize  the  thickness  of 
the  gathering,  collects  upon  .the  end,  or  nose,  as  it  is 
technically  called,  a pear-shaped  lump  of  glass.  Best- 
ing his  pipe  upon  a stand  or  horse,  he  turns  it  gently 
around  and  allows  the  surface  of  the  lump  to  cool,  to  be 
flt  for  a second  gathering.  So  much  glass  is  collected 
in  this  way  in  successive  layers  as  will  form  a disc 
or  table  of  about  nine  pounds  weight,  which  an  ex- 
perienced workman  can  easily  guess  ; the  lump  com- 
pleted, the  gatherer  having  cooled  his  pipe  under  a 
trough  of  water,  that  he  may  handle  it  at  any  point, 
proceeds  to  roll  the  glass  upon  a marver  until  it  as- 
sumes a conical  form,  the  apex  of  the  cone  forming 
whaf  is  termed  a bullion-point.  A boy  now  blows 
down  the  pipe  while  it  is  still  being  turned  by  the  gath- 
erer on  the  marver,  and  expands  the  glass  into  a small 


WINDOW  GLASS. 


239 


globe.  Having  been  heated,  it  is  blown  again,  and 
assumes  the  shape  of  a florence  flask,  and  the  future 
rim  of  the  developed  plate  or  disc  is  prepared  by 
rolling  i\\Q>  piece ^ as  tlie  glass  under  operation  is  termed, 
near  the  pipe  hose  upon  the  edge  of  the  marver. 
Again  heated,  it  is  now  expanded  by  the  blower  into 
a large  globe  ; again  presented  to  the  fire,  by  the  pe- 
culiar manipulations  of  the  workman  and  the  peculiar 
direction  of  the  flame  upon  it,  the  front  of  the  globe 
is  flattened,  the  possibility  of  the  globe  collapsing 
during  this  operation  being  prevented  by  its  rapid 
revolution  around  its  axis.  The  piece  now  resembles 
somewhat  in  shape  an  enormous  decanter,  with  a 
very  flat  bottom  and  a very  short  neck.  The  pipe  is 
laid  horizontally  upon  an  iron  rest,  and  a man  ap- 
proaches, having  in  his  hand  the  large  rod,  the  ponty, 
tipped  with  a lump  of  molten  glass  ; pressing  this 
lump  upon  an  iron  point  so  as  to  give  it  the  form  of  a 
little  cup,  he  fits  it,  wlien  thus  shaped,  on  to  the  bul- 
lion-point, to  which  it  soon  becomes  flrmly  attached  ; 
the  lump  thus^formed  is  called  the  bull’s-eye  or  bullion 
of  the  developed  plate.  The  incision  of  a piece  of  cold 
iron  in  the  glass  around  the  nose  of  the  pipe,  and  a 
smart  blow,  soon  detaches  the  pipe,  leaving  a corres- 
ponding hole  in  the  flattened  sphere  at  a point  exactly 
opposite  the  attachment  of  the  ponty  ; the  blowing 
pipe  thus  removed,  and  carrying  with  it  a piece  of 
glass,  is  allowed  to  lie  idle  a few  minutes,  till  the  glass 
adhering  to  it  has  cracked  off;  it  is  then  warmed  and 
carried  back  to  the  pot  to  repeat  its  course  in  a simi- 
lar operation.  The  open  projecting  end  of  the  piece 
which  w’as  next  the  now  detached  pipe,  is  called  the 
nose,  and  gives  its  name  to  the  furnace  or  nose-hole. 


240 


ART  OF  GLASS  MAKING. 


It  is  now  the  glass  undergoes  its  last  operation.  A 
man  stands  in  front  of  a huge  circle  of  flame,  termed 
the  flashing  flame,  into  which  he  tlirusts  his  piece 
rapidly,  meanwhile  revolving  his  ponty.  The  action 
of  heat  and  centrifugal  force  combined  is  soon  visible. 
The  nose  of  the  piece  or  hole  caused  by  the  removal 
of  the  blowing  pipe  enlarges,  the  parts  around  cannot 
resist  the  tendency,  the  opening  grows  larger  and 
larger.  For  a moment  is  caught  a glimpse  of  a circle 
with  a double  rim  ; the  next  moment  before  the  eyes 
of  the  astonished  spectator  is  whirling  a thin  transpa- 
rent circular  plate  of  glass,  which  but  a few  minutes 
before  was  lying  in  the  glass  pot. 

A flat  circular  disc,  nearly  sixty  inches  in  diameter, 
or  sometimes  more,  is  produced,  of  almost  uniform 
thickness,  except  at  the  point  of  attachment  to  the 
ponty,  where  there  is  a swelling  called  the  bull’s-eye. 
Still  whirling,  the  table,  as  it  is  now  called,  is  carried 
off,  laid  flat  upon  a support  called  a whimsey,  detached 
by  shears  or  otherwise  from  the  ponty,  and  lifted  into 
the  annealing  kiln  upon  a fork.  As  the.jJ)ull’s-eye  or 
centre  lump  which  the  ponty  has  left  behind  it  keeps 
each,  table  from  close  contact  with  its  neighbors,  the 
air  passes  freely  between  them,  and  the  annealing  is 
completed  with  tolerable  rapidity,  varying  from  24  to  48 
hours,  according  to  the  number  of  tables  in  the  kiln. 
From  the  kiln  the  tables  are  conveyed  to  the  ware- 
house, having  passed  since  their  flrst  exit  from  the  pot 
through  the  hands  of  ten  distinct  workmen. 

The  improvement  in  the  details  of  the  operation 
have  produced  a difterent  result  from  that  of  former 
times. 

In  the  warehouse,  the  tables  are  laid  upon  a o^est  or 


PLATE  GLASS. 


241 


ciisliion,  and  are  divided  by  tlie  diamond  of  the  split- 
ter into  two  unequal  parts,  the  larger  half  containing 
the  bnll’s-eye.  The  diameter  of  the  table  is  measured 
on  the  rest,  the  usual  size  being  now  about  54  inches, 
and  weighing  thirteen  pounds  ; tables  have  been  made 
as  high  as  seventy  inches,  but  the  difficulty  of  manipu- 
lation, and  the  uncertainty  of  the  result,  render  such 
sizes  too  costl}^  to  be  general. 

The  splitter  carefully  examines  each  table  before 
splitting,  and  turns  it  around  until  he  has  brought  it 
into  the  position  in  which  he  may  split  it  to  the  best 
advantage,  announcing  at  the  same  time  its  quality. 

ly.  Plate  Glass. — This  glass  is  formed  by  being 
castor  founded  upon  a smooth  table,  while  in  a liquid 
state,  and  is  totally  independent  of  the  process  of 
blowing.  It  is  not  generally  known  that  originally 
all  plate  glass  was  made  by  blowing,  and  not  until 
1773  was  this  glass  cast  in  England,  while  in  France 
the  process  has  been  used  for  one  hundred  years.  The 
method  formerly  adopted  was  the  same  as  the  blown 
sheet  glass ; the  plates  then  produced  were  much 
smaller  than  can  be  executed  by  the  casting  process, 
which  sometimes  exceed  ten  feet  in  length,  and  about 
half  an  inch  thick.  Plates  have  been  cast  as  much  as 
fourteen  feet  long  by  eight  to  ten  in  width.  The 
principal  consumption  of  plate  glass  is  for  mirrors. 

In  composition  this  plate  glass  is  similar  to  cro'wn 
and  sheet  glass,  the  only  essential  bases  being  lime  and 
soda  ; the  plate  glass  has  the  soda  in  excess,  for  the 
reason  that  it  imparts  a higher  degree  of  fluidity,  and 
because  the  impurities  which  it  contains  are  more 
readily  dissipated  by  the  heat,  so  that  the  use  of  soda, 


242 


ART  OF  GLASS  MAKING. 


though  objectionable  as  tending  to  color  the  glass,  fa- 
cilitates both  the  lining  and  casting. 

Plate  glass  consists  bj  analysis  of — 


Silica, 

75.9 

Alumina, 

2.8 

Lime, 

3.8 

Soda, 

17.5 

It  differs  considerably  from  window  glass  in  the 
proportions ; it  is,  therefore,  more  fusible,  more  readily 
altered,  and  less  hard  than  window  glass,  and  it  is  also 
less  brittle,  and  less  liable  to  be  devitrilied. 


The  French  plate  glass  consists  of — 


Pure  sand, 

100  lbs. 

Sal  soda. 

35 

u 

Lime, 

5 

a 

Broken  glass. 

100 

a 

Decoloring  matter. 

1 

u 

Another  French  formula  is  : 

Sand, 

100  lbs. 

Sal  soda, 

60 

u 

Carbonate  of  lime. 

13 

ii 

Broken  glass. 

100 

(( 

Peroxide  manganese, 

1 

u 

Puly.  smalt. 

i 

a 

The  English  formula  is : 

The  best  washed  sand  and  dried, 

720 

parts. 

Alkaline  salt  of  40  p.  c , soda. 

450 

u 

Slaked  and  sifted  lime. 

80 

(( 

Flitre, 

25 

(( 

Broken  glass, 

425 

u 

PLATE  GLASS. 


243 


This  whole  mixture  of  one  pot  of  metal  yields  one 
thousand  and  two  hundred  pounds  of  glass.  The  main 
object  of  getting  a fine  metal  is  by  giving  the  most 
perfect  transparency  to  mirrors,  and  to  destroy  the 
slightest  traces  of  coloration  ; not  alone  must  the 
metal  or  melted  glass  be  thoroughly  fused,  but  the 
original  materials  must  be  selected  with  great  care. 
The  sand  must  be  very  white  and  tine  ; flint  and  quartz 
reduced  to  tine  powder  will  suit  well ; the  soda  per- 
fectly pure,  so  as  to  avoid  the  green  tint  which  soda 
is  apt  to  impart. 

The  melting  and  lining  is  performed  in  two  sizes  of 
pots ; the  larger  is  for  melting  the  vitreous  mixture 
and  for  keeping  it  long  in  a state  of  fusion  ; the 
smaller  for  receiving  a portion  of  the  glass  to  be  lined 
and  cast,  called  cuvette  or  cistern.  Furnaces  for 
casting  plate  glass  are  constructed  to  hold  six  pots  and 
twelve  cuvettes,  eight  small  and  four  large  ones  ; the 
small  ones  have  the  form  of  a perfect  square,  the  large 
ones  of  an  oblong  rectangle. 

The  ingredients  for  plate  glass  are  fritted  before 
melting,  and  then  put  in  the  pots  in  three  successive 
charges ; the  material  is  left  sixteen  hours,  and 
during  the  melting  of  the  mixture  in  the  pots,  the 
cuvettes  are  placed  empty  in  the  furnace,  but  as  soon 
as  the  whole  charge  is  in  a state  of  fusion,  the  cuvettes 
are  removed  by  means  of  tongs  and  cleansed  from  all 
impurities  by  a scraper,  and  are  placed  in  the  furnace, 
and  after  a few  minutes  heating,  the  ladling  or  trans- 
ferring operation  commences.  The  surface  of  the 
metal  in  the  pots  is  skimmed,  and  the  liquid  glass  is 
transferred  into  the  adjacent  cuvette  with  a copper 
ladle,  care  being  taken  not  to  disturb  any  grains  of 


244 


ART  OF  GLASS  MAKING. 


sand  or  lumps  that  may  have  settled  down  on  the 
bottom  of  the  pot.  The  ladling  is  performed  by  two 
men  ; each  draws  out  the  glass  three  times,  and  then 
plunges  his  ladle  into  cold  water.  The  furnace  is 
then  shut,  and  the  cuvettes  are  left  to  theipselves  for 
the  glass  to  fuse,  or  the  bubble  sproduced  in  the  mass 
by  the  process  of  ladling  or  trejetage  may  be  disen- 
gaged, and  the  excess  of  soda  entirely  volatilized.  The 
melting  lasts  sixteen  hours,  and  the  fining  also  as  long, 
and  extends  from  24  to  48  hours,  or  until  all  the  bubbles 
are  dispersed,  and  until  specimens  of  the  glass  exhibit 
in  every  respect  a fit  state  for  casting. 

The  casting  process  is  as  follows : 

While  the  glass  is  acquiring  the  requisite  con- 
sistence, the  annealing  furnaces  and  the  slabs  or 
metal  plate  upon  which  is  to  be  received  the  liquid  glass, 
must  be  heated.  The  casting  slab  is  now  made  of 
iron,  and  as  large  as  to  weigh  50,000  pounds,  and  cost 
100,000  fcs.,  and  is  from  10  to  20  feel;  in  length,  and 
the  same  in  breadth,  and  from  6 to  7 inches  thick,  and 
rests  on  a strong  wooden  frame,  movable  on  castors, 
or  a rail-road,  and  is  wheeled  from  one  annealing 
furnace  to  the  other.  The  height  of  the  slab  is  made 
exactly  on  a level  with  the  fioor  of  the  arch  of  the 
annealing  furnace ; its  upper  surface  is  fiat  and  pol- 
ished, to  mould  the  lower  surface  of  the  mirror,  and 
before  the  casting  it  is  heated  by  hot  coals  spread  over 
it,  and  then  wiped  perfectly  clean. 

The  annealing  ovens  being  heated  to  a brown  red, 
the  casting  slab  brought  to  a suitable  temperature, 
and  the  metal  or  melted  mass  thickened  to  the  requi- 
site point  for  flowing  readily  and  equably,  the  aperture 


PLATE  GLASS, 


245 


into  tlie  cuvettes, . which  are  to  be  taken  oat,  is  then 
opened,  and  two  workmen  introduce  tongs  into  the 
farnace,  and  grasp  the  cuvette  by  the  groove,  while  a 
third  slides  a large  pincer  under  it.  When  that  iu- 
struinent  is  pushed  well  under  the  bottom  of  the  cu- 
vette, the  workman  draws  it  towards  him,  aided  by 
the  others  with  their  tongs,  which  are  supported  on 
rollers ; in  this  manner  the  cuvette  is  drawn  to  the 
month  of  the  opening,  where  it  is  raised  by  a crane, 
j)laced  upon  a truck  or  low  carriage,  and  removed  to 
the  casting  table ; the  melted  glass  being  §kimmed, 
the  cuvette  is  then  drawn  up  to  a sufficient  height  by 
a tackle,  and  suspended  above  the  upper  end  of  the 
casting  table,  where  it  is  tilted  over  by  means  of  the 
tongs,  and  the  metal  is  poured  out  on  the  table.  The 
appearance  presented  by  the  molten  sheet  is  now  ex- 
ceedingly splendid  ; the  glass  is  prevented  from  run- 
ning over  the  sides  by  ribs  or  rims  of  copper,  which 
are  exactly  equal  in  height  to  the  intended  thickness 
of  the  plate  of  glass,  and  when  the  cuvette  has  been 
emptied  of  its  contents,  a massive  hollow  copper  c}din- 
der,  three  feet  in  diameter,  and  resting  on  each  end  on 
the  side  ribs,  is  set  in  motion.  This  cylinder,  which 
weighs  several  hundred  ^veight,  is  moved  by  means 
of  the  handles,  wdiich  form  a prolongation  of  the  axis, 
and  spreads  the  glass  out  into  a sheet  of  uniform 
breadth  and  thickness.  To  prevent  any  impurity 
from  contaminating  the  glass,  a workman  drawls  the 
w’asher  covered  with  cloth  immediately  in  front  of  the 
advancing  sheet  of  fluid  glass,  the  excess  of  glass  pours 
over  the  front  edge  of  the  slab  into  a trough  filled 
w'ith  w^ater,  and  finally  the  roller  passes  off,  and  is  re- 
ceived in  the  grooves. 


2i6 


ART  OF  GLASS  MAKING. 


A beautiful  plaj  of  brilliant  colors,  comprising  every 
tint  imaginable,  is  exhibited  by  the  glass  immediately 
after  the  roller  has  passed  over  it,  probably  caused  by 
a temporary  oxydation  of  the  surface.  While  the  in- 
troduction of  the  plate  into  the  annealing  furnace  is 
being  proceeded  with,  other  workmen  are  engaged  in 
taking  from  the  fining  furnace  another  cuvette,  which 
arrives  at  the  casting  table  at  the  moment  when  the 
preceding  plate  has  just  been  introduced  into  the  an- 
nealing oven.  After  filling  the  oven,  all  the  openings 
are  carefully  stopped  up  with  iron  plates  and  clay 
mixed  with  sand.  At  the  end  of  twenty  hours  some 
of  the  pieces  of  iron  are  taken  away  ; an  hour  or  two 
afterwards  more  are  removed  ; as  the  oven  cools,  more 
and  more  are  taken  away,  and  at  last  the  whole  of 
the  clay  and  plates  of  iron  which  stopped  the  aper- 
tures are  removed.  When  the  hand  can  be  placed 
on  the  glass  plates  without  feeling  much  heat,  they 
may  be  taken  out  of  the  oven. 

The  plates,  after  being  withdrawn  from  the  anneal- 
ing oven,  have  to  undergo  the  operation  of  squaring^ 
grinding  polishing  j as  taken  from  the  oven,  they 
are  about  half  an  inch  thick,  and  present  an  irregular 
mottled  appearance,  roughened  on  the  lower  surface 
by  the  sand  on  which  they  have  rested,  and  smoother, 
but  not  flat  on  the  upper  surface.  The  first  process 
is  that  of  squaring,  or  cutting  them  into  their  useful 
dimensions,  and  the  workmen  endeavor,  notwithstand- 
ing the  imperfect  transparency  of  the  glass,  ‘to  select 
those  which  appear  to  be  free  from  defects,  while 
such  as  show  imperfections  that  cannot  be  removed 
by  grinding,  are  picked  out  to  be  cut  into  smaller 
plates. 


PLATE  GLASS. 


24:7 


The  squaring  is  performed  by  passing  a rougli  dia- 
mond along  the  surface  of  the  glass,  guided  by  a square 
rule;  the  diamond  cuts  to  a certain  depth  into  the 
substance,  when,  by  gently  striking  the  glass  with  a 
hammer  underneath  the  part  which  is  cut,  the  piece 
comes  away,  and  the  roughness  of  the  edge  then  left 
is  removed  by  pincers.  The  plates  having  been 
squared,  undergo  then  the  process  of  grinding  and 
polishing.  Two  plates  are  employed,  one  of  larger 
dimensions,  and  one  three  or  four  times  smaller,  which 
are  made  to  rub  against  each  other,  which  is  done  by 
machinery  ; the  lower  and  longer  plate  is  imbedded  in 
Plaster  of  Paris  in  a perfectly  horizontal  position  upon 
a table  about  two  feet  high,  termed  the  grinding  henohj 
the  smaller  plate  is  cemented  upon  the  lower  face  of 
a swing  table,  made  heavy  by  weights,  and  caused  to 
traverse  over  the  lower  plate  in  such  a way -that  by  a 
combination  of  a rotary  and  oscillating  motion,  the 
relative  position  of  the  two  plates  is  constantly 
changed.  In  adjusting  the  plates,  a rough  or  rolled 
surface  of  the  one  is  opposed  to  the  comparatively 
smooth  or  casting  plate  surface  of  the  other,  and  the 
material  employed  to  grind  the  surfaces  is  'thrown 
upon  the  lower  plate  from  time  to  time  ; ground  flint 
of  different  sizes  is  used  for  this  purpose ; the  ma- 
chinery is  set  in  motion  by  a steam  engine,  and  the 
process  is  continued  until  the  ground  plates  exhibit  a 
perfectly  horizontal  and  even,  though  still  unpolished 
surface.  When  one  side  of  the  plate  has  been  suffi- 
ciently ground,  it  is  loosened  from  the  frame  and 
turned  over,  so  as  to  present  the  other  surface  to  be 
ground  in  the  same  manner.  Some  degree  of  pressure 
is  employed,  by  loading  the  upper  plate  with  weights, 


248 


ART  OF  GLASS  MAKING. 


as  the  grinding  of  each  side  approaches  to  completion. 
The  process  is  now  performed  in  less  than  three  days. 
The  plates  require  now  another  polish,  which  is  done 
by  grinding  them  with  emery  powder  of  increasing 
degrees  of  fineness  ; after  the  application  of  the  last 
or  finest  emery,  the  plate  has  become  quite  smooth 
and  partly  polished.  The  glass,  although  now  per- 
fectly even,  appears  opaque  and  deadened  on  the  sur- 
face, and  still  requires  the  final  polishing.  To  effect 
this,  a piece  of  wood  is  covered  with  numerous  folds 
of  woollen  cloth,  so  as  to  form  an  elastic  cushion, 
which  is  fitted  with  a handle  ; the  plate  is  imbedded  in 
Plaster  of  Paris,  as  already  stated,  and  the  cushion 
being  wetted,  is  covered  with  a fine  earthy  matter- 
consisting  of  crocus  martis^  and  is  moved  backwards 
and  forwards  on  the  surface  of  the  plate  with  con- 
siderable pressure.  By  the  grinding  and  polishing, 
the  plates  are  reduced  as  much  as  one-third,  and  if 
any  radical  defects  exist  in  the  glass,  these  are  only 
heightened  by  the  polishing;  those  which  are  still 
found  defective  after  tlie  polishing,  are  cut  up  into 
smaller  plates  and  polished  again,  while  the  perfect 
ones,  when  destined  for  mirrors,  are  subjected  to  a 
final  process,  wdiich  is  the  silvering  of  mirrors,  which 
is  done  by  a compound  of  tinfoil  and  mercury.  The 
operation  is  commenced  by  spreading  a sheet  of  tinfoil, 
which  must  be  of  somewhat  larger  dimensions  than  the 
plate  to  be  covered,  upon  a fiat  stone  or  slate  slab, 
termed  the  silvering  table,  and  brushing  mercury  over 
it.  When  the  surface  of  the  tinfoil  is  uniformly 
covered,  more  mercury  is  added,  till  it  covers  the  me- 
tallic sheet  to  the  depth  of  one-sixth  or  one-quarter  of 
an  inch.  This  process  is  also  a tedious  one,  and  very 


PLATE  GLASS. 


249 


dangerous  for  the  workmen,  and  a new  process  lias 
latterly  been  substituted,  by  employing  a silvering 
fluids  obtained  by  mixing  ammonia  with  nitrate  of 
silver,  and  adding  to  it  an  alcoholic  solution  of  some 
essential  oil,  like  oil  of  cloves,  cassia,  &c.,  with  a cer- 
tain portion  of  grape  sugar  ; this  fluid  has  the  property 
of  depositing  bright  metallic  silver,  on  the  addition  of 
the  reducing  liquid,  consisting  of  the  alcoholic  solution 
of  one  part  oil  to  three  parts  alcohol,  and  two  parts 
grape  sugar.  Another  reducing  liquid  is  composed  of 

2 parts  of  nitrate  of  silver. 

3 water. 

1 “ ammonia. 

To  this  mixture  is  added  one-fourth  part  of  grape 
sugar,  dissolved  in  weak  spirit.  For  coating  the  inte- 
rior of  glass  balls,  &c.,  gun  cotton,  dissolved  in  caustic 
potassa,  with  the  aid  of  heat,  adding  to  the  brown  so- 
lution a few  drops  of  nitrate  of  silver  and  the  ammo- 
nia, until  the  precipitated  oxide  of  silver  is  re-dissolved  ; 
this  mixture  is  introduced  into  the  glass  ball  or  other 
vessel  to  be  loricated,  and  heated  in  a w^ater  bath, 
when,  after  a certain  time,  the  mixture  becomes  black- 
ish brown,  froths  up  and  deposits  all  the  silver  upon 
the  glass,  forming  a mirror  which  is  said  to  reflect  the 
light  wdth  surpassing  brilliancy.  The  latest  method, 
however,  is  used  by  adding  a certain  quantity  of  Eo- 
chelle  salt,  in  solution,  to  the  ammoniated  silver  of 
the  above  proportions,  without  the  aid  of  grape  sugar 
or  oil  of  cloves. 


250 


ART  OF  GLASS  MAKING. 


Petit  jean’s  Method  of  Silvering  Glass. 

For  one  hundred  superficial  feet  of  plate  glass,  a 
mirror  was  completed  in  forty  hours,  while  the  opera- 
tion usually  occupied  ten  days. 

Prepare  two  argentiferous  solutions  ; the  first  has 
180  parts  of  nitrate  of  silver,  which,  treated  with  62 
parts  of  liquid  ammonia  of  870°  spec,  gravity,  and 
500  parts  distilled  water,  the  whole  is  then  filtered^; 
this  solution  is  afterwards  diluted  with  sixteen  times 
its  volume  of  distilled  water,  to  which  is  added  drop 
by  drop  seven  parts  of  tartaric  acid,  (Kochelle  salt  has 
been  employed  in  this  country  and  found  preferable,) 
previously  dissolved  in  thirty  parts  of  water ; this 
liquid  is  marked  No.  1 solution. 

The  second  solution  is  prepared  precisely  the  same, 
only  containing  double  the  quantity  of  tartaric  acid 
or  Eochelle  salt. 

The  plate  glass  being  cleaned  with  putty  powder 
mixed  with  water,  and  spread  over  the  entire  surface 
with  a ball  of  chamois  leather,  or  a soft  linen  cloth, 
and  leaving  it  to  dry  for  a few  minutes,  and  then  rub- 
bing it  oflF  with  another  piece  of  chamois,  the  glass  is 
placed  on  a rack,  and  an  India  rubber  roller,  moistened 
with  distilled  water,  passed  over  it,  to  remove  any 
particles  of  rust  that  may  adhere  to  it.  After  this,  it 
is  laid  upon  a metallic  table,  covered  with  a wax 
or  varnished  cloth,  and  heated  to  about  120°.  The 
plate  being  in  a perfectly  horizontal  position,  its  sur- 
face is  covered  with  No.  1 solution  ; the  deposition  of 
silver  commences  in  about  ten  minutes,  and  is  com- 
pleted in  fifteen  minutes  afterwards.  The  glass  is  then 
tilted  up,  so  as  to  allow  the  liquor  to  run  oflF,  and 


FLINT  GLASS. 


251 


rinsed  with  water  more  than  lukewarm,  to  carry  away 
the  non-adherent  powder.  It  is  then  restored  to  its 
horizontal  position,  and  covered  with  No.  2 solution. 
In  a quarter  of  an  hour  the  deposit  is  completed.  It 
is  now  washed  as  before  and  dried,  after  which  it  only 
remains  to  polish  and  burnish  the  film  of  silver  de- 
posited, in  order  to  make  it  perfectly  smooth,  and  give 
closeness  to  the  grain. 

In  the  last  Paris  Exhibition,  the  finest  specimens  of 
plate  glass  were  exhibited  ; one  plate  measured  twenty 
feet  by  twelve  feet ; one  silvered  mirror  of  nearly  the 
same  size ; the  glass  for  them,  and  several  other  plates, 
was  melted  in  a single  pot,  capable  of  holding  a ton  of 
the  fused  metal.  The  tin  foil  used  for  silvering 
weighs  two  pounds  for  every  square  meter. 

A large  mammoth  plate  glass  w^as  lately  imported 
from  France,  which  measured  twenty  feet  long  and 
sixteen  feet  eight  inches  wide  ; it  is  not  intended  as  a 
mirror  or  window,  but  to  represent,  under  a strong 
liglit,  a frozen  lake  in  a theatrical  scene. 

Y.  Flint  Glass. — This  is  generally  termed  crystal 
glass,  on  account  of  its  resemblance  to  rock  crystal, 
the  natural  mineral ; it  is  chiefly  manufactured  into 
articles  of  domestic  use  and  ornament,  such  as  tum- 
blers, decanters,  wine-glasses,  vases,  drops  for  chan- 
deliers, &c.  In  consequence  of  its  great  transparency 
and  high  refractive  power,  it  is  also  formed  into  lenses 
for  optical  instruments.  It  is  also  called  flint  glass, 
on  account  of  the  employment  of  the  flint,  which  is 
found  in  the  chalk,  as  the  source  of  the  silica;  for  the 
sands  are  not  only  more  free  from  iron,  but  less  ex- 
pensive in  the  preparation  than  flints,  when  washed 
and  calcined.  The  flint  glass,  properly  speaking,  is  a 


252 


ART  OF  GLASS  MAKING. 


lead  or  metal  glassjin  distinction  from  the  other  varie- 
ties of  glass,  and  is  distinguished  from  crown  and  plate 
glass  by  the  use  of  potassa,  instead  of  soda,  in  the 
manufacture. 

The  term  crystal,  or  flint  glass,  is  now  known  to 
denote  the  double  silicate  of  potassa  and  lead.  It  is 
well  understood  that  the  colorless  crystal,  or  lead  glass 
of  the  present  day,  or,  in  other  words,  a crystal  pos- 
sessing that  quality,  which  constitutes  its  chief  beauty 
and  value,  is  entirely  of  a modern  invention.  The 
analysis  of  the  flint  glass  gives — 


Silica, 

56.0 

Lime, 

2.6 

Oxide  of  lead, 

32.5 

Potassa, 

8.9 

100.0 

Many  metallic  oxides  are  capable  of  combining  with 
silicic  acid,  and  thus  furnishing  silicates  which  readily 
mix  wnth  alkaline  silicates,  but  almost  all  these  are 
colored.  Till  lately,  the  protoxide  of  lead  and  the 
oxide  of  bismuth  were  regarded  as  the  only  oxides 
capable  of  yielding  silicates  with  little  color,  and  con- 
sequently colorless  glasses,  by  their  mixture  with  the 
silicate  of  potassa  in  a proper  proportion  ; but  a glass 
of  zinc,  which  had  a very  pleasing  and  white  appear- 
ance, and  was  specially  suited  for  achromatic  purposes, 
has  been  shown  to  have  the  remarkable  property  of 
being  of  greater  specific  gravity,  and  much  more  pure 
and  pellucid  than  lead  glass. 

Well  prepared  crystal  or  flint  glass  is  alnqost  with- 
out color,  is  more  transparent,  more  brilliant,  and 


FLINT  GLASS. 


253 


heavier  than  plate  or  window-glass.  It  excels  the 
fine  Bohemian  crown  glass  in  refractive  power  and 
easy  fusibility,  although  the  latter  is  harder  and  more 
completely  colorless.  Flint  glass  of  not  less  than  the 
usual  density  of  3.200,  well  polished,  is  considered 
the  nearest  approach  to  the  diamond  ; it  owes  its  bril- 
liancy and  high  density  to  the  silicate  of  lead  ; but  as 
the  latter  is  in  itself  yellow,  it  communicates  a yellow 
tint  to  the  crystal,  when  it  preponderates  over  the 
alkaline  silicate  beyond  a certain  limit. 

It  is  a common  mistake  to  suppose  that  great  den- 
sity or  weight  is  an  advantage  in  crystal  for  articles  of 
common  use  ; it  is,  on  the  contrary,  a real  inconveni- 
ence, and  in  the  most  favorable  view,  can  only  be  con- 
sidered as  a ready  means  of  showing  that  the  crystal 
or  fiint  glass  contains  enough  of  silicate  of  lead  to  im- 
part to  it  all  the  other  qualities,  which  give  it  its  pe- 
culiar value,  and  renders  it  preferable  to  other  glasses 
for  certain  purposes.  As  lead  affords  the  only  me- 
tallic oxide  which  is  usually  employed  in  the  manu- 
facture of  fiint  glass,  so  potassa  is  the  only  alkali  which 
can  be  successfully  associated  with  that  ingredient  to 
yield  a colorless  glass.  The  silicate  of  soda  always 
communicates  a blue  or  green  tinge,  which  would  be- 
come more  perceptible  and  disagreeable  in  the  thick 
articles  usually  manufactured  of  crystal.  Crystal  ves- 
sels are  generally  intended  to  receive  mouldings,  or 
cut  ornaments,  and  do  not  admit  of  being  made  thin 
in  the  sides.  The  annealing  would  also  become  difii- 
cult  in  vessels  of  considerable  size,  without  a propor- 
tionate thickness.  Crystal  is  so  fusible,  that  it  is  not 
easy  to  prevent  such  articles  from  sinking  in  or  col- 
lapsing during  the  annealing.  Tliis  kind  is,  therefore, 

12 


254 


ART  OF  GLASS  MAKING. 


exclusively  confined  to  the  manufacture  of  thick  arti- 
cles, and  hence  it  is  only  the  colorless  silicates  that 
can  be  used,  namely,  those  of  lead  or  zinc,  and  potassa. 

A good  common  flint  glass  is  the  following  two  for- 
mulas, the  one  with  coal,  and  the  other  with  wood  as 
fuel : 


Sand,  washed  and  calcined, 

COAL. 

100 

WOOD. 

100 

Red  lead. 

70 

45 

Purified  potassa. 

30 

35 

Cullet, 

100 

100 

Saltpetre  or  arsenic, 

2 

2 

Oxide  manganese. 

3 

3 

A highly  pellucid  and  transparent  flint  glass  is  ob- 
tained of— 

Carbonate  of  potassa,  one  hundred  weight. 

Red  lead  or  litharge,  two  “ “ 

Sand,  washed  and  burnt,  three  “ 

Saltpetre,  from  14  to  28  pounds. 

Oxide  manganese,  from  4 to  12  ounces. 

Cullet  at  discretion. 

The  best  French  formula  is— 

Pure  sand,  300  parts. 

Red  lead,  215  ‘‘ 

Purified  carb.  potassa,  110  “ 

Nitrate  of  potassa,  10  “ 

Borax,  12 

The  lowest  proportion  of  red  lead  that  can  be  used, 
is  in  the  following  formula: 


FLINT  GLASS. 


255 


Sand, 

Ked  lead, 

Garb,  potassa. 
Gullet, 

Arsenious  acid. 
Oxide  manganese. 


300  parts. 
180  ‘‘ 
120 

300  ‘‘ 

45 
60 


The  utmost  attention  must  be  paid  to  have  the  ma» 
terials  in  a perfect  state  of  purity  ; the  sand  should  be 
very  white,  and  free  from  coloring  oxides  of  iron  and 
manganese ; it  ought  to  be  washed  with  diluted  hydro- 
chloric acid,  and  undergo  eight  washings  of  water,  and 
afterwards  pass  through  a heated  coil  called  a calker, 
so  that  it  is  perfectly  dry.  The  carbonate  of  potassa 
requires  likewise  a thorough  purification,  by  dissolv- 
ing it  in  water,  decanting  the  clear  solution,  and 
evaporating  to  dryness.  The  red  oxide  of  lead  must 
be  made  from  pure  metallic  lead,  for  the  commercial 
is  never  perfectly  pure,  but  contains  copper,  iron  and 
other  oxides  in  too  large  a quantity.  The  few  ounces 
of  manganese  are  employed  to  neutralize  the  greenish 
tint  produced  by  the  presence  of  iron  or  other  impuri- 
ties. The  fiint  glass  furnaces  are  generally  round, 
and  contain  from  eight  to  twelve  pots. 

It  is  also  advisable  to  have  two  furnaces,  instead  of 
one,  both  opening  into  the  same  flue,  for  the  reason, 
while  one  of  the  furnaces  is  in  full  operation,  the 
other  may  be  undergoing  repair ; or  the  working  of 
one  may  be  entirely  suspended,  wfithout  injury  to  the 
other,  during  a dullness  of  trade.  Each  of  the  furnaces 
may  be  capable  of  holding  eight  pots.  Their  shape  is 
distinguished  from  those  employed  for  other  descrip- 
tions of  glass,  by  being  covered  with  a hood-shaped 


256 


ART  OF  GLASS  MAKING. 


top,  the  mouth  of  which  fits  the  working  holes  of  the 
furnace,  so  that  the  smoke  and  heat  cannot  escape  in 
the  same  way  as  in  the  usual  glass  furnaces. 

In  France  open  pots  are  used  for  fiint  glass,  and  as 
fuel,  dry  beech  or  oak  wood  ; so  little  carbon  is  pro- 
duced from  the  smoke  as  not  to  afiect  materially  the 
metal,  although  the  flames  play  upon  its  surface ; but 
when  coal  or  coke  is  used,  the  fumes  and  smoke 
emitted  would  carbonize  or  deoxydize  the  lead,  and 
precipitate  it  to  the  bottom  in  the  original  metallic 
state,  if  the  pots  were  not  covered ; besides  that,  the 
solid  particles  of  soot  would  blacken  the  glass,  by 
attaching  themselves  firmly  to  its  surface. 

The  melting  pots  usually  hold  about  1,800  weight 
each,  and  the  batch  or  frit  is  introduced  in  them  by 
means  of  shovels  in  quantities  of  four  hundred  weight 
at  a time,  allowing  a sufficient  interval  between  each 
filling  for  melting  down  the  various  charges,  until  the 
pot  is  entirely  filled  with  fused  glass.  In  about  twelve 
to  fifteen  hours  every  pot  in  the  furnace  is  fully 
charged  with  liquid  metal ; air  bubbles*  and  striae 
then  abound,  and  are  not  expelled  until  thirty  or  forty 
hours  more  have  elapsed,  when  the  mass  becomes  ho- 
mogeneous. The  best  results  depend  upon  an  intense 
and  continuous  fusion,  for  too  little  caloric  will  fail  to 
refine  the  metal. 

During  the  founding,  the  mouths  are  securely 
stoppered  and  clayed  up ; the  shorter  the  time  of  fusion 
and  refining  the  better ; for  this  purpose  the  heat  can 
scarcely  be  too  great. 

If  the  glass  does  not  get  fine  by  the  usual  time  al- 
lotted, but  becomes  cottled  o|^gelatinous,  it  never  will 
recover,  however  urged  by  subsequent  fusion  ; such 


FLINT  GLASS. 


257 


glass  must  be  ladled  into  water,  and  considered  only 
as  cullet,  for  a re-fusion  with  a proportion  of  new  ma- 
terials. The  moment  the  metal  is  fully  fused  and  re- 
fined by  continuous  rapid  fusion,  the  high  temperature 
of  the  furnace  should  be  reduced  from  its  maximum 
heat  to  a working  temperature,  this  period  being  con- 
sidered the  crisis. 

The  mechanical  operations  connected  with  common 
bottle  glass,  crown,  sheet  and  plate  glass,  are  uniform 
in  their  character  ; the  description  of  the  making  of 
one  bottle,  or  of  one  table,  sheet  or  plate  glass,  applies 
to  all ; the  infinite  variety  of  shapes  into  which  com- 
mon fiint  glass  or  crystal  is  manufactured,  would  be 
very  tedious  to  explain.  That  glass  is  either  formed 
by  simple  blowing  with  the  pipe,  and  then  shaping 
by  hand  or  by  blowing  in  moulds,  or  by  moulds  alone, 
in  which  the  glass  is  subjected  to  pressure.  In  each 
of  these  cases  the  form  and  appearance  of  the  articles 
are  mostly  improved  by  grinding,  cutting,  &c. 

A tumbler,  for  instance,  may  be  made  by  hand. 
The  workman  collects  on  the  end  of  a pipe  a small 
quantity  of  glass,  which  is  now  rounded  on  the  marver, 
expanded  by  blowing,  or  somewhat  elongated  by 
swinging,  when  it  assumes  the  pear  form ; the  pipe  is 
then  suspended  vertically,  and  the  glass  is  allowed  to 
drop  by  its  own  weight  upon  the  marver,  which  flat- 
tens it  at  the  extremity,  and  being  at  the  same  time 
further  blown,  assumes  a bottle  form.  The  pipe,  with 
a portion  of  the  glass,  is  then  detached,  by  touching 
the  piece  with  a cold  pucellas ; this  contracts  and 
slightly  fractures  the  glass,  which  is  subsequently 
cracked  through  the  entire  circumference  by  a smart 
blow  of  the  same  instrument.  In  the  meantime  the 


258 


AKT  OF  GLASS  MAKING. 


ponty  has  been  attached  by  adhesion  to  the  flat  end, 
and  the  other  end  is  flrst  expanded  with  the  pucellas, 
and  then  sheared  otf  so  as  to  make  it  perfectly  even, 
and  fit  it  for  the  flashing  or  finishing  ; finally,  it  is 
knocked  off  from  the  ponty  by  a sharp  blow,  and  taken 
to  the  annealing  arch.  Wine  glasses  are  usually  made 
in  three  pieces,  but  the  process  is  the  same  as  for 
tumblers.  The  moulds  for  flint  glass  are  carefully 
constructed  of  brass  or  iron,  and  when  of  simple  con- 
struction are  somewhat  wider  at  the  upper  end,  so  that 
the  pieces  may  be  easily  removed,  or  are  composed  of 
more  than  one  piece,  when  projecting  parts  are  to  be 
moulded.  A common  open  and  shut  mould,  as  is 
used  for  apothecaries’  vials,  as  well  as  for  common  wine 
bottles,  are  formed  by  two  halves,  connected  with  a 
bottom  hinge;  the  glass  to  be  moulded  is  gathered  on  the 
pipe,  rolled  on  the  marver  into  a cylindrical  form,  and 
then  pinched  with  the  pucellas  at  the  end  attached  to 
the  pipe,  to  form  the  neck  of  the  bottle ; the  cylindrical 
mass,  still  adhering  to  the  pipe,  is  then  inserted  into 
the  mould  lying  on  the  ground,  its  two  halves  are  shut, 
and  the  workman  blows  through  the  tube,  which 
renders  the  mass  of  glass  hollow,  while  it  receives 
from  the  mould  the  external  form  required. 

The  third  method  of  manipulation  with  flint  glass, 
is  moulding  by  pressure,  which  consists  in  dropping 
the  soft  metal  into  a prepared  die,  and  then  pressing 
down  the  matrix  or  plunger  upon  it  by  means  of  a 
lever. 

The  finishing  process  given  to  the  finer  articles 
manufactured  of  flint  glass  is  the  cutting  and  polish- 
ing^ or  more  properly  grinding  this  operation  is  per- 
formed by  discs  of  iron,  sandstone  or  copper,  revolving 


FLINT  GLASS. 


259 


in  a lathe,  which  is  usually  propelled  by  steam ; the 
edges  of  the  discs,  which  are  sharp,  angular  or 
rounded,  according  to  the  work  to  be  performed,  are 
supplied  with  sand  and  water  dropping  from  a hopper 
for  rough  grinding,  and  with  emery  for  fine  grinding. 
A stone  wheel  with  water  is  employed  to  smooth  out 
the  rough  sand  marks,  and  prepares  the  glass  for  the 
polishing,  which  is  effected  b}^  means  of  a willow- wood 
disc,  first  with  a mixture  of  pumice  and  rotten  stone, 
and  finishing  with  a preparation  of  tin  and  lead  or 
glass  putty;  all  table  glassware  and  hollow  articles 
are  thus  cut.  Chandelier  drops  are  cut  or  ground  with 
iron  and  stone  wheels  in  the  same  manner,  but  are 
finished  with  a lead  wheel,  supplied  with  fine  rotten 
stone  and  water. 

Small  copper  discs  of  the  size  of  a half-penny  and 
finely  pulverized  emery  mixed  with  oil  are  used  to 
execute  the  outline  and  ground  of  the  glass  engravers’ 
work,  and  for  polishing,  lead  wheels  and  very  finely 
pulverized  emery  are  employed.  Coarse  patterns  for 
hall  lamps  are  engraved  by  the  glass  cutters’  smooth- 
ing wheels.  For  inscribing  initials,  coats  of  arms  and 
minute  designs,  very  small  discs  must  be  employed. 
The  finest  incisions  are  made  with  copper  pencils, 
either  pointed  or  ending  in  a button-like  disc. 

The  etching  on  glass  is  performed  by  hydrofiuoric 
acid,  either  in  the  gaseous  or  liquid  state,  and  exerts  a 
peculiar  action  on  glass,  which  has  been  turned  to 
account  as  a substitute  for  cutting  or  engraving  designs. 
For  etching  on  glass  by  means  of  hydrofluoric  acid, 
the  glass  is  cleaned  and  a melted  varnish  poured  upon 
it,  which  is  spread  in  a homogeneous  coating;  the 
varnish  is  formed  of  wax  and  turpentine,  say  one  part 


260 


ART  OF  GLASS  MAKING. 


of  the  latter  to  four  parts  of  wax ; a burin  is  then 
passed  over  the  varnish,  following  the  lines  of  the 
figure  and  cutting  through  the  varnish  to  the  glass ; 
when  the  figure  is  traced,  the  glass  is  ready  to  be 
exposed  to  the  action  of  the  hydrofluoric  acid,  which, 
according  to  the  strength,  requires  from  five  seconds  to 
five  minutes ; the  varnish  is  then  removed  by  melting 
it  with  heat,  and  the  glass  is  then  wiped  off  with  a 
soft  linen  rag.  A finer  varnish  is  required  for  more 
delicate  designs  and  shades,  which  is  a fat  copal 
varnish,  blackened  with  lampblack,  which  must  be 
quite  fine,  and  sprinkled  with  oil  of  turpentine;  the 
coatings  laid  on  must  be  very  thin,  and  each  should 
be  quite  dry  before  putting  on  a new  one.  The  glass 
is  sufiiciently  covered  with  varnish  when  the  light  can 
scarcely  be  seen  to  pass  through  it ; the  design  is  then 
copied  through,  and  the  varnish  is  removed  from  the 
lines  with  the  points  of  gravers,  or  simple  needles,  of 
dififerent  sizes  and  forms.  This  portion  of  the  glass 
enables  one  to  perceive  the  most  delicate  lines.  After 
having  formed  the  figure,  it  must  be  corroded  out 
with  liquid  hydrofluoric  acid.  By  a preliminary 
experiment  or  a coin-strip  of  glass,  the  time  will  be 
easily  ascertained,  which  is  required  to  be  used  on  the 
article  when  the  design  is  to  be  executed.  Hydroflu- 
oric acid,  diluted  with  soft  water,  one  part  of  the  first 
to  six  parts  of  the  latter,  is  unquestionably  the  best 
material  for  cleaning  plate  glass  and  any  other  glass 
which  may  be  sooty,  or  have  any  flaws  on  tlie  surface. 

Optical  Glass. — The  most  serious  difiSculty,  which 
has  to  this  day  impeded  the  progress  of  improvement 
of  optical  instruments  of  the  highest  order,  has  been 
the  imperfection  of  glass.  It  is  one  which  is  so  far 


OPTICAL  GLASS. 


261 


from  betraying  to  ordinary  observers  the  faults,  which 
make  it  useless  to  the  optician,  when  the  specimens 
which  seem  most  brilliant  are  not  seldom  those  which 
are  in  this  respect  most  faulty.  Two  kinds  of  glass, 
crown  and  flint  glass,  are  combined  in  the  construction 
of  achromatic  lenses.  Crown  glass  is  only  composed 
of  silex,  potassa  and  lime,  while  in  flint  glass  the  oxide 
of  lead  is  added.  The  unequal  density  of  these  two 
glasses  prevents  their  forming,  while  in  a state  of 
fusion,  amass  of  uniform  character;  the  heavier  of 
the  two  tends  to  sink  to  the  bottom  of  the  crucible, 
and  the  result  is  to  produce  a compound  of  very  une- 
qually refracting  power.  Nearly  flfty  years  ago  the 
great  English  philosophers,  Faraday,  Herschel  and 
Dollond,  entered  into  experimental  inquiry,  for  the 
purpose  of  devising  means  of  overcoming  such  a great 
difliculty  ; which,  however,  did  not  advance  the  prac- 
tical object  in  view,  although  the  results  of  their  in- 
vestigations were,  in  many  respects,  highly  interesting. 
The  largest  telescopic  objective  of  satisfactory  per- 
formance did  not  exceed  flve  to  six  inches  in  diameter. 
At  the  Paris  Exposition  of  1867,  the  most  brilliant  dis- 
play of  optical  glasses  was  exhibited,  which  have  quite 
satisfactorily  proved  the  equal  density  and  uniformity 
of  refractory  power.  The  process  is  made  known  to 
consist  of  uniting  numerous  small  selected  masses  of 
glass  of  ascertained  equality  into  one  large  mass  by 
pressure,  while  in  a plastic  condition  ; it  resembles  the 
process  of  the  welding  of  iron,  and  the  great  problem 
is  now  fully  solved.  The  same  manufacturer  exhibited 
several  specimens  of  the  silico-borate  of  lead,  a glass 
of  great  speciflc  gravity,  and  which  he  calls  heavy  glass^ 
its  specific  gravity  varying  from  4.20  to  5.44. 

12* 


262 


ART  OF  GLASS  MAKmQ. 


great  magnificent  disc  of  flint  glass  of  over 
twenty-eight  inches  was  also  exhibited.  At  the  same 
Exposition  a great  variety  of  glass  plates  were  exhibit- 
ed ; one  of  them,  by  actual  measurement,  was  found  to 
have  the  dimensions  of  nineteen  feet  and  six  inches  by 
eleven  feet. 

The  exhibition  of  prisms  was  very  excellent ; very 
large  four  inch  right-angled  prisms,  and  some  rock 
crystal  prisms,  suitable  for  the  study  of  the  fluorescent 
rays  beyond  the  violet ; also,  hollow  prisms  for  ex- 
periments on  transparent  fluids,  were  formed  of  plates 
of  plain  glass  united  without  cement,  being  made 
water-tight  by  the  perfection  and  polish  of  their 
surfaces. 

For  illustrating  the  laws  of  refraction,  were  prisms 
with  horizontal  axes  of  variable  angles  for  fluids. 

The  best  proportions  for  an  optical  glass  are  the 
following  : 

For  flint  glass : 


Sand, 

43.5 

Bed  lead, 

43.5 

Carbonate  potassa, 

10. 

Nitrate  potassa, 

3. 

100. 

For  crown  glass : 


Sand, 

60 

Carbonate  soda. 

25 

Carbonate  lime. 

14 

Arsenic, 

1 

100 


ZINO  OPTICAL  GLASS. 


263 


It  will  be  observed,  that  optical  flint  glass  is  chiefly 
distinguished  by  the  large  proportion  of  lead  which 
enters  into  its  composition  ; its  density  should  not  be 
lower  than  3.6  at  least.  The  essential  point  in  the 
manufacture,  however,  consists  in  the  constant  stirring 
of  the  metal  during  the  melting  and  fusing.  The 
superiority  of  Guinaud’s  plan  is  considered  not  to 
have  been  in  the  novelty  of  the  materials  or  propor- 
tions, but  in  carefully  agitating  the  liquid  glass  while 
at  the  highest  point  of  fusion,  then  cooling  down  the 
entire  contents  of  the  pot  in  a mass,  and  when 
annealed  and  cool,  separating  unstriated  portions  by 
cleavage.  Faraday’s  heavy  glass,  which  has  proved  so 
important  in  experiments  connected  with  the  polari- 
zation of  light  by  magnetic  action,  is  composed  of  the 
following  ingredients  : 


Protoxide  of  lead, 

104 

Silicate  of  lead, 

24 

Dry  boracic  acid. 

25 

This  glass  required  but  a red  heat  for  fusion,' 
tliereby  offering  facilities  for  minute  agitating  opera- 
tions; it  was  found,  however,  not  to  be  durable,  and 
not  calculated  for  application  to  optical  purposes  or 
general  use. 

Zinc  Optical  Glass. — The  basis  of  this  vitreous  com- 
pound is  the  oxide  of  zinc,  a certain  quantity  of  borax 
or  boracic  acid  being  added  to  give  tlie  glassy  charac- 
ter for  whicli  the  boracic  compounds,  no  less  than  the 
silica,  are  so  eminently  remarkable,  combined  with  an 
easier  fusibility  ; it  is  suitable  for  the  crown  glass  in 
achromatic  telescopes,  but  not  for  the  flint  glass  ; the 


264 


ART  OF  GLASS  MAKING. 


low  dispersive  power  of  the  zinc  compound,  points  to 
the  use  of  glass  of  zinc  for  this  purpose. 

YI.  Strass  and  Colored  Glass. — The  manufacture  of 
glasses  tinged,  colored  or  stained  by  different  processes, 
has  become  a business  of  great  and  growing  import- 
ance. The  taste  for  stained  glass  windows,  which 
formed  so  distinguished  a feature  in  the  history  of  a 
former  period,  has  revived,  and  is  now  displayed  in 
the  decoration  not  only  of  splendid  palatial  and 
ecclesiastical  structures,  but  even  of  many  private 
dwellings,  steamers,  &c.  The  skill  of  the  Yenetians  of 
a former  day  in  producing  colored  vases  and  other 
ornamental  articles  of  glass  of  every  variety  of  hue, 
is  equaled,  if  not  surpassed,  in  modern  times ; artificial 
gems  or  pastes,  which  are  true  glasses,  are  now  formed, 
that  emulate,  if  they  do  not  eclipse  in  sparkling  lustre 
and  pure  transparency,  the  rarest  and  most  beautiful 
natural  productions  of  the  mineral  kingdom. 

The  basis  of  the  color,  or  that  with  which  the 
coloring  matter  is  actually  mixed,  is  a lead  glass,  and 
this,  when  real  glass  painting  is  the  object,  is  applied 
either  as  a pigment,  or  in  a melted  state  on  common 
glass  or  some  other  finished  article  ; in  other  cases 
the  colored  lead  glass  is  itself  formed,  cut  or  moulded 
into  the  finished  article.  When  the  latter  is  an  artifi- 
cial gem  or  paste,  a peculiar  glass  is  employed  termed 
strass y which  it  may  be  proper  to  describe  now.  This 
paste,  having  its  name  from  the  inventor,  constitutes 
the  only  true  glass  not  yet  hinted  at  in  this  treatise, 
but  forms  the  basis  of  artificial  imitations  of  precious 
stones.  Tor  this  purpose  a glass  is  required,  possess- 
ing the  highest  degree  of  purity  and  transparency, 
combined  with  the  greatest  possible  lustre.  These 


STEASS  AND  COLORED  GLASS. 


265 


requirements  are  found  in  a composition  analogous  to 
that  of  flint  glass,  but  containing  a much  larger  pro- 
portion of  oxide  of  lead  and  a little  boracic  acid.  The 
three  following  mixtures  are  recommended  : 


Ground  rock  crystal. 

ONE. 

100 

TWO. 

THREE. 

100 

Sand, 

— 

100 

— 

Pure  red  lead. 

156 

— 

154 

White  lead. 

— 

171 

— 

Purifled  caustic  potassa, 

54 

32 

56 

Boracic  acid. 

7 

9 

6 

Arsenious  acid. 

3 

3 

16  ^ 

The  oxide  of  lead  is  in  excess  of  all  other  glass,  even 
optical  flint  glass.  When  strass  is  well  prepared,  it 
possesses  as  nearly  as  possible  the  high  refractive 
power,  and  all  the  other  properties  of  the  diamond, 
except  its  hardness.  When  cut  into  shape  without 
any  coloring,  it  answers  for  imitating  the  diamond  ; and 
when  tinged  by  silicates  with  metallic  bases,  it  fur- 
nishes imitations  of  all  the  colored  stones. 

Its  perfect  purity  and  high  lustre  are  the  essential 
requisites,,  and  for  this  reason  requires  great  care  in 
the  choice  of  the  materials.  A pottery  furnace  and 
Hessian  crucibles  are  used  for  melting  the  material, 
which  is  to  be  kept  in  the  Are  for  twenty-four  hours; 
the  more  tranquil  and  prolonged  the  fusion,  the 
greater  hardness  and  beauty  does  the  strass  acquire. 

The  coloring  materials  used  for  the  imitation  of 
gems,  are  the  following  : 

Yellow  is  produced  either  by  charcoal,  antimony, 
silver,  or  oxide  of  uranium ; a very  superior  yellow, 


266 


ART  OR  GLASS  MAKING. 


by  roasting  the  sulphide  of  antimony  to  the  state  of 
antimonious  acid,  or  the  white  oxide  of  antimony,  and 
melting  it  with  from  three  to  live  per  cent,  of  unde- 
composed  sulphide  of  antimony.  An  orange  yellow  is 
obtained  by  glass  of  antimony,  red  lead,  and  a little 
oxide  of  iron  ; in  these  cases  the  substances  so  pre- 
pared are  mixed  with  the  materials  of  the  glass. 
When  silver  is  employed,  the  process  is  quite  differ- 
ent. In  this  case  a mixture  of  powdered  clay  and 
chloride  of  silver  is  applied  to  the  surface  of  the  ready- 
made articles,  and  on  reheating  these  in  a muffle,  the 
silver  penetrates  to  a certain  depth  into  the  glass,  even 
before  the  latter  softens  ; the  article  is  then  allowed 
to  cool,  and  the  coating  which  was  applied  is  scraped 
off,  when  a yellow  color  of  great  purity  and  brilliancy 
appears  on  the  glass  ; very  remarkable  it  is  that  this 
effect  can  only  be  produced  on  glass  containing  alu- 
mina, which  shows  that  it  is  a chemical,  and  not  me- 
chanical action.  Oxide  of  uranium  produces  a beauti- 
ful delicate  yellow  of  a slightly  greenish  hue.  E-ed  of 
different  shades  is  communicated  by  oxide  of  iron, 
sub-oxide  of  copper,  or  different  preparations  of  gold, 
mixed  with  other  materials ; the  oxide  of  iron  is  em- 
ployed, either  as  pure  oxide,  prepared  by  heating 
the  nitrate,  or  in  the  state  of  red  hematite  or  ochre ; 
it  produces,  if  added  to  the  glass  mixture,  a cheap  and 
very  common  brownish  red.  The  peculiar  action  of 
sub-oxide  of  copper  was  much  employed  by  the  artists 
of  the  fifteenth  and  sixteenth  centuries,  for  producing 
the  brilliant  red  colors  of  window  panes  ; and  in  later 
times  the  glass  so  colored  was  supposed  to  be  indebted 
to  gold  for  its  beautiful  rich  hue.  So  intense  is  the 


STRASS.AKD  COLORED  GLASS. 


26T 


coloring  power  of  this  oxide,  that  even  a very  small 
quantity  reddens  the  glass  so  much,  as  to  render  it 
opaque,  and  hence  it  is  almost  impossible  to  command 
any  desired  tint  in  applying  it ; recourse  is  had,  to  ob- 
viate this  difficulty,  to  the  process  of  flashing^  or  coat- 
ing with  colored  glass. 

The  application  of  gold  for  producing  a brilliant  red 
color,  which  can  be  made  to  assume  a scarlet,  carmine, 
rose  or  ruby  tint,  has  long  been  known,  having  been 
made  by  precipitating  a solution  of  chloride  of  gold 
wdth  a salt  of  the  sesquioxide  of  tin,  under  the  name  of 
cassius  jpurple  y the  simple  addition  of  a solution  of 
gold  to  a flux,  without  any  oxide  of  tin,  is,  however, 
capable  of  producing  rose  and  carmine  colored  glass. 

Blue  is  produced  by  oxide  of  cobalt,  a pigment 
which  is  equally  applicable  to  lead  glass  and  to  glass 
containing  no  lead.  The  coloring  power  of  the  oxide 
of  cobalt  is  so  intense,  that  pure  white  glass  is  made 
sensibly  blue  by  the  addition  of  one  thousandth  part 
of  the  oxide.  Smalt  and  zaffre  are  but  impure  oxides 
of  cobalt. 

Green  is  produced  either  by  protoxide  of  iron,  pro- 
toxide of  copper,  or  oxide  of  chromium.  The  tint 
produced  by  the  first  has  little  brilliancy.  The  oxide 
of  copper  gives  a beautiful  emerald  ; for  this  purpose 
the  glass  is  mixed  with  the  product  obtained  by  heat- 
ing copper  to  redness  with  access  of  air,  or  with 
powdered  verdigris,  which  is  then  decomposed  in 
the  fire  and  converted  into  oxide  by  oxydizing  agents. 
Care  must  be  taken  to  prevent  the  protoxide  of  iron 
from  being  converted  into  sesquioxide,  and  the  oxide 
of  copper  from  being  reduced  to  sub-oxide. 


268 


AET  OF  GLASS  MAKING. 


Artificial  Gems. — The  following  is  a formula  for  the 
production  of  artificial  gems  : 

Diamond. — Colorless  strass  without  any  addition. 

Toj)az. — White  strass,  1000 

Clear  orange  red  glass  of  antimony,  40 
Purple  of  cassius,  1 

Also  of  strass,  1000 

Oxide  of  tin,  10 

Ruby. — This  is  the  rarest  and  most  highly  priced 
of  artificial  stones ; the  mixture  for  topaz  often  gives 
an  opaque  mass,  translucid  at  the  edges  and  presenting 
in  its  tliin  plates  a color  red  by  transparency.  One 
part  of  this  opaque  mass  and  eight  parts  of  strass, 
melted  in  a Hessian  crucible,  when  left  30  hours  in 
the  fire  of  a potter’s  furnace,  gi  ve  a fine  yellowish  crystal 
similar  to  strass.  Remelted  with  the  blow-pipe,  this 
produces  rubies  of  the  first  water.  A ruby  not  so 
fine  and  of  a different  tint  may  be  made  by  employing 
the  following  proportions : 

Colorless  strass,  1000 

Oxide  of  manganese,  25 

Emerald. — It  is  very  easy  to  imitate  ; the  mixture 

of  oxide  of  copper  with  colorless  strass  gives  the  best 

results,  and  if  oxide  of  cobalt  is  added,  the  green 
obtained  presents  blue  reflections. 

The  composition  which  gives  the  best  imitation  of 
natural  emerald  is  as  follows : 

Colorless  strass,  1000 

Pure  oxide  of  copper,  8 

Oxide  of  chromium,  0.2 

By  increasing  the  proportion  of  chromium  or  oxide 


ARTIFICIAL  GEMS. 


269 


of  copper,  and  adding  oxide  of  iron  to  the  mixture, 
one  may  vary  the  green  shade,  and  imitate  peridot  or 
dark  emerald. 

Sapphire. — To  produce  a fine  oriental  blue  color, 
one  must  employ  very  white  strass  and  very  pure 
oxide  of  cobalt.  The  composition,  put  into  a luted 
Hessian  crucible,  should  remain  30  hours  in  the  fire. 
The  proportions  are  as  follows  : 

Colored  strass,  1000 

Oxide  of  cobalt,  15 

Amethyst. — The  color  of  this  stone  must  be  fine 
and  velvety,  to  be  of  any  value.  The  formula  which 
succeeds  best  is  the  following  : 


Colorless  strass,  1000 

Oxide  of  manganese,  8 

Oxide  of  cobalt,  5 

Purple  of  Cassius,  0.2 


Aquamarine. — It  is  of  pale  emerald  tint,  but  the 
most  valuable  kind  is  colorless  like  the  diamond.  It 
is  obtained  artificially : 

Colorless  strass,  1000 

Glass  of  antimony,  T 

Oxide  of  cobalt,  0.4 

Syrian  Garnet  or  Carbuncle. — It  has  a lively  color, 
and  is  much  used  for  small  jewels.  The  artificial  garnet 
is  a kind  of  dark  ruby,  and  is  made  after  the  follow- 


ing formula : 

Colorless  strass,  1000 

Glass  of  antimony,  500 

Purple  of  cassius,  4 

Oxide  of  manganese,  4 


270 


AKT  OF  GLASS  MAKING. 


In  the  manufacture  of  artificial  stones,  there  are 
many  precautions  to  be  taken,  and  many  points  to  be 
observed,  which  can  only  be  acquired  by  experience. 
The  materials  must  be  finely  pulverized.  The  mix- 
tures can  only  be  well  made  by  repeated  sifting.  To 
obtain  masses  well  melted,  without  any  strise  or  bub- 
bles, it  is  necessary  to  employ  the  purest  substances, 
to  use  the  best  crucibles,  to  melt  with  a graduated 
heat  in  a furnace  which  is  quite  equal  to  its  maximum 
temperature,  to  leave  the  metal  in  the  furnace  at  least 
from  24:  to  30  hours,  and  to  cool  the  crucibles  very 
slowly,  that  their  contents  may  undergo  a kind  of 
annealing. 

So/^  WAiU  Enamel. — To  600  weight  of  batch  add 
twenty-four  pounds  of  arsenic  and  six  pounds  of  anti- 
mony. 

Hard  White  Enamel. — To  600  weight  of  batch  add 
200  pounds  of  putty  prepared  from  tin  and  lead. 

Blue  Transparent  Glass. — To  600  weight  of  batch 
add  two  pounds  oxide  of  cobalt. 

Azure  Blue. — To  600  weight  of  batcli  add  six 
pounds  of  oxide  of  copper. 

Ruhy  Red. — To  600  weight  of  batch  add  four 
ounces  of  oxide  of  gold. 

Amethyst  or  Purple. — To  600  weight  of  batch  add 
twenty  pounds  of  oxide  of  manganese,  (pure.) 

Common  Orange. — To  600  weight  of  batch  add 
twelve  pounds  of  iron  ore  and  four  pounds  of  man- 
ganese. 

Emerald  Green. — To  600  weight  of  batch  add 
twelve  pounds  of  copper  scales  and  twelve  pounds  of 
iron  ore. 

Gold  Paper  Color. — To  600  weight  ofi  batch  add 


FLASHED  GLASS. 


271 


three  pounds  of  oxide  of  uranium.  Under  a batch  is 
understood  the  mixture  of  materials,  such  as  that  for 
flint  glass  as  noticed  in  previous  pages. 

Flashing  and  Casing, — Heferring  to  the  sub-oxide 
of  copper,  it  was  remarked  that  the  coloring  power 
was  so  intense,  that  even  a very  small  quantity 
wmuld  render  the  glass  opaque,  and  that  the  process 
of  flashing  had  to  be  resorted  to,  in  order  to  overcome 
the  difficulty.  This  process  consists  in  coating  a layer 
of  colorless  with  one  of  colored  glass,  which  can  then 
be  reduced  by  grinding  to  the  proper  tint.  For  this 
purpose  the  glass-blower  collects  the  proper  quantity 
of  colorless  glass  on  the  end  of  his  pipe,  rolls  it  upon 
the  marver,  and  then  dips  it  for  a moment  into  a pot 
of  melted  colored  glass,  and  blows  out  the  two  together 
into  a cylinder  or  globe,  wdiich  is  flattened  or  flashed 
out  in  the  usual  manner,  which  is  the  way  how  panes 
for  the  glass  painter  are  formed,  which  consist  of  two 
layers  of  glass,  one  colored  the  other  colorless,  and 
the  former  can  be  ground  down  to  any  required  tint 
or  degree  of  transparency.  An  ingenious  application 
of  this  process  is  made  to  vessels  of  flint  glass,  which 
are  colored  on  ^the  outside  in  a similar  manner,  and 
colorless  edges  or  facets  are  then  produced  by  cutting 
through  the  outer  layer  of  colored  glass  into  the  sub- 
stratum of  colorless  glass. 

. Flint  glass  is  colored  in  a similar  manner,  by  the 
process  called  casing,  in  the  following  manner  : If  any 
two  or  more  glasses  intended  for  casing  have  been 
mixed  of  the  same  specific  gravit}^  to  give  them  the 
capability  of  harmonizing,  tliat  is,  of  contracting  and 
expanding  equally,  the  blower  has  to  gather  a ball  of 
solid  glass  intended  for  the  interior  layers  in  the  usual 


272 


ART  OF  GLASS  MAKING. 


manner,  wliicli  may  be  considered  to  be  of  white 
crystal  glass ; about  the  same  time  his  assistant  pre- 
pares a casing  of  colored  glass,  knocking  off  the  knob 
to  open  and  shape  it,  somewhat  like  the  bowl  of  a 
wine-glass,  or  the  broad  end  of  a large  egg-shell ; this 
is  set  in  a metal  stand  on  the  floor,  merely  to  steady 
the  case  or  shell,  while  the  blower  takes  the  lump  of 
flint  or  white  glass,  and  gently  blows  it  into  the  co- 
lored ease  or  shell,  to  which  it  immediately  adheres, 
and  when  submitted  to  a pot  hole,  it  is  found  to  weld 
perfectly. 

Yenetian  Filagree  work  is  produced  in  the  follow- 
ing manner  : Pieces  of  cane,  or  solid  rods  of  glass  of 
different  colors,  having  been  drawn  out  in  the  same 
manner  as  tubes,  and  whetted  off  to  the  required 
lengths,  are  arranged  in  the  flutes  or  internal  grooves 
of  a cylindrical  mould ; the  blower  then  inserts  a solid 
ball  of  transparent  flint  glass,  and  the  whole  is  exposed 
to  a welding  heat  till  the  canes  adhere  to  the  ball ; 
both  are  then  withdrawn  with  it  from  the  mould. 

The  Venetian  Ball  is  simply  a number  of  pieces  of 
waste  filagree  glass  collected  together  without  regular 
design. 

The  Millefiore^  or  star  work  of  the  Yenetians,  is 
formed  by  placing  lozenges  of  glass  cut  from  the  ends 
of  colored  filagree  canes  in  the  interval  between  two 
transparent  canes. 

Glass  Mosaic  is  produced  by  threads  or  small  canes 
of  variously  colored  opaque  or  transparent  glass  of 
uniform  lengths,  ranged  vertically  side  by  side  in 
single  threads  or  masses,  so  that  the  ends  shall  form 
grounds  agreeably  to  some  prefigured  design. 

Yenetian  Frosted  Glass  is  obtained  by  immersing  the 


GLASS  PAINTING. 


273 


gathering  of  hot  metal  in  cold  water,  quickly  with- 
drawing it,  reheating  and  expanding  it  by  blowing 
before  it  becomes  so  hot  as  to  melt,  and  weld  together 
the  numerous  superficial  cracks  produced  by  the 
momentary  immersion  in  cold  water;  these  cracks 
onlj^  penetrate  as  far  as  the  metal  has  been  cooled  by 
the  water,  and  remains  as  depressions  until  the  article 
is  finished. 

Avanturin  Glass  is  an  easily  fusible  brown,  or  in 
thin  layers,  yellow  glass,  interspersed  with  spangles  or 
numerous  fine  yellow  laminse  with  a metallic  lustre, 
which  give  it  a peculiar  shining  appearance.  The 
manufacture  was  long  kept  a secret  by  the  Yenetians. 
It  was  commonly  supposed  that  avanturin  glass  was 
produced  by  melting  scales  of  metal  or  mica  with  the 
glass  ; but  when  examined  under  the  microscope,  these 
scales  appeared  as  regular  three  or  six  sided  tables, 
perfectly  crystaline  in  structure ; and  it  was  ascertained 
that  the  spangles  consisted  of  metallic  copper  crj^stal- 
ized  in  the  form  of  fiat  seo;ments  of  a regular  octahe- 
dron.  The  following  mixture,  after  fusing  together  for 
twelve  hours,  produce  a good  result : 

Pounded  glass,  300  parts. 

Copper  scales,  40  “ 

Iron  scales,  80  “ 

The  fused  mass  must  be  cooled  slowly ; the  glass 
obtained  is  somewhat  deficient  of  lustre,  but  it  con- 
tained copper  diffused  through  the  mass  in  octahedral 
crystals. 

Glass  Painting, — Painting  on  glass  is  performed 
by  means  of  a vitreous  mixture  termed  tlie  flux,  com- 


274 


ART  OF  GLASS  MAKING. 


bined  with  a pigment  prepared  from  some  metallic 
oxide ; the  flux  and  oxide  are  simply  that  combination 
of  ingredients  which  is  necessary  to  produce  a highly 
fusible  colored  glass  of  the  required  hue  ; this  mixture 
is  reduced  to  a state  of  flne  powder  rubbed  up  in  oil 
of  turpentine,  boiled  oil,  or  sometimes  simply  with 
water,  and  laid  upon  the  glass  to  be  painted  by  means 
of  a brush;  the  glass  thus  painted  or  stained  with 
the  intended  design  is  then  exposed  to  a heat  sufticient 
to  vitrify  the  mixture  of  color  and  flux,  without  melt- 
ing the  glass ; in  other  words,  the  painting  is  said  to 
be  burnt  in,  the  ingredients  of  which  it  is  composed 
are  converted  into  a colored  glass  or  transparent 
picture,  while  the  pane  or  other  article  on  which  it  is 
laid  is  only  sufficiently  softened  to  cause  the  complete 
adherence  of  the  colored  glass  to  its  surface. 

The  fusing  point  of  the  pigment  must  be  much 
lower  than  that  of  the  glass  to  be  painted ; it  is  even 
necessary  that  the  former  should  vitrify  at  a tempera- 
ture at  which  the  latter  does  not  sensibly  soften,  for 
any  considerable  softening  or  yielding  of  the  glass 
would  distort  the  design  ; hence  the  manifest  inappli- 
cability of  crystal  on  lead  glass  for  painted  articles, 
on  account  of  its  great  fusibility.  Common  window  or 
plate  glass  may  be  successfully  used,  and  best  of  all, 
the  hard  Bohemian  glass,  which  contains  potassa  for  a 
base.  The  flux  is  usually  composed  of  the  following 
ingredients ; 

Quartz  in  powder,  100  parts. 

Oxide  of  lead,  125  “ 

Oxide  of  bismuth,  50  “ 


SPUN  GLASS. 


275 


Bat  if  these  oxides  exert  an  injurious  action  on  the 
colorinoj  matter,  and  tend  to  change  its  shade,  the  sub“ 
joined  composition  is  used  : 


Carbonate  of  lime,  free  from  iron,  12.5  “ 

To  each  of  these  mixtures  or  fluxes  the  proper  co- 
loring matter  is  added,  and  the  composition  so  formed 
is  introduced  into  a crucible  and  melted  into  a colored 
glass;  the  latter  is  then  reduced  to  a fine  powder, 
mixed,  as  has  been  stated,  with  oil  of  turpentine,  and 
used  as  a common  pigment  for  painting  on  the  less 
fusible  glass.  In  this  operation  a cartoon,  or  drawing 
upon  paper,  is  placed  below  the  glass,  and  the  colors 
are  applied  on  the  corresponding  lines.  In  preparing 
painted  sheets  or  panes  of  glass,  brown  or  black  out- 
lines are  generally  traced  on  the  one  side  of  the  sheet, 
while  tho  colors  are  laid  on  the  other  side ; but  in 
painting  vessels  or  other  articles,  this  is  not  the 
practice. 

Sjpun  Glass. — The  art  of  spinning  glass  consists  in 
drawing  it  out  into  threads,  when  softened,  by  means 
of  a wheel  on  which  the  thread  is  wound ; the  drawn 
out  end  of  a glass  rod  has  only  to  be  attached  to  a re- 
volving drum,  while  the  rod,  whence  the  thread  pro- 
ceeds, is  held  in  the  glass-blower’s  lamp,  in  order  to 
obtain,  in  a few  minutes,  several  yards  of  spun  glass. 

Glass  from  Cryolite, — An  opaque  glass,  or,  as  it  has 
been  called  by  the  manufacturers,  ‘‘  hot  cast  porcelain,” 
has  been  introduced  a few  years  ago  in  this  country 


Quartz  in  powder. 
Fused  borax, 
Nitrate  of  potassa. 


100  parts, 
75 

12.5  “ 


276 


ART  OF  GLASS  MAKING. 


by  a company  who  purchased  the  monopoly  from  the 
Danish  Government  for  exporting  the  mineral  cryolite 
from  Greenland.  This  species  of  glass  is  composed  of 
ten  pounds  crjmlite,  twenty  pounds  white  sand,  and 
five  pounds  of  oxide  of  zinc,  which  composition  is 
well  mixed  and  exposed  in  the  furnace  at  the  same 
high  temperature  as  any  other  flint  glass.  We  have 
seen  a great  variety  of  utensils  cast  in  moulds  of  tiles, 
mantelpieces,  statuary,  mortars,  evaporating  dishes, 
pill  tiles,  funnels,  ointment  jars,  and  many  other  arti- 
cles, capable  of  being  cast,  blown,  or  moulded,  whilst 
in  a melted  state,  and  at  a mere  trifling  cost,  and  to 
all  appearance  have  the  advantages  over  many  other 
wares  now  in  use.  Mortars  have  stood  the  pounding 
and  trituration  better  than  a wedgewood  mortar,  and 
the  evaporating  dishes  resisted  the  heat  of  both  the 
sand  and  water  baths,  and  all  at  about  half  the  cost 
of  ordinary  porcelain.  Lamp  shades,  and  other  fine 
parlor  ornaments,  finished  in  the  best  manner,  and 
slabs  of  six  feet  long  and  four  feet  wide,  without  a 
fault,  the  writer  saw  in  the  sample  room  of  Ihe  com- 
pany. This  glass  or  porcelain  bids  fair  to  supersede 
the  French  porcelain  for  toughness,  strength  and  capa- 
bility of  standing  sudden  changes  of  temperature. 

The  manufactory  has  lately  been  suspended,  and 
the  causes  of  failure  are  unknown  to  the  writer. 

YII.  Soluble  Glass. — This  glass  has  been  fully  ex- 
plained in  the  first  part  of  this  book ; the  various 
modes  of  manufacture,  and  various  kinds,  and  the  va- 
rious uses. 

It  is  stated  a simple  silicate  of  potassa  or  soda,  or  a 
double  silicate  of  these  two  bases.  This  body  is  solu- 


CHEMICAL  PROPERTIES. 


277 


ble  in  boiling  water,  without  a residue,  and  scarcely 
affected  by  contact  with  cold  water. 

The  soluble  silicated  alkali,  also  called  water  glass, 
may  be  obtained  in  various  ways,  as  also  explained 
before  ; at  present,  some  large  manufacturers  employ 
powdered  flints,  which  are  dissolved  in  a caustic  lye 
at  a temperature  of  300°.  This  water  glass  has  found, 
lately,  special  application  : 1.  In  protecting  building 
stone  from  decay.  2.  In  hardening  cements  or  mor- 
tar, so  as  to  render  them  impermeable  by  water.  And 
3.  For  stereo-chromic  painting.  It  is  specially  used 
as  a protective  varnish  for  pictures ; as  a Are  and  rot 
proof  coating  for  all  building  materials  of  organic 
origin,  such  as  timbers,  &c.,  and  inorganic  matter. 

The  Chemical  Properties  of  Glass. — Among  the 
chemical  properties  of  glass,  there  are  some  which 
merit  an  attentive  examination : 1.  The  effect  of  the 
air  or  deoxydizing  bodies.  2.  That  of  water.  3.  That 
of  acids.  4!  That  of  bases  on  glass. 

Air  or  oxygen,  cold  or  hot,  provided  they  are  dry, 
exercise  no  action  on  glasses.  Not  so  with  moist  air ; 
as  has  been  stated  above,  the  case  is  with  the  soluble 
glass. 

It  is  evident  that  deoxydizing  bodies  may  act  with 
the  aid  of  heat  on  glasses  which  contain  oxides  of  iron 
or  manganese,  especially  lead.  When  plumbous 
glasses  are  heated  with  charcoal,  or  in  a current  of 
hydrogen,  they  very  readily  undergo  a remarkable 
alteration  ; the  oxide  of  lead  is  reduced,  and  the  metal 
being  set  free,  communicates  to  the  glass  a blackish 
tint ; this  effect  is  so  rapid,  that  we  cannot  operate  on 
crystal  glass  at  the  enameler’s  lamp,  without  blacken- 
ing it  greatly. 


13 


278 


ART  OF  GLASS  MAKING. 


The  action  of  water  is  more  or  less  on  all  glasses  ; 
it  tends  to  decompose  it  into  a soluble  alkaline  silicate, 
and  an  insoluble,  earthy  and  alkaline  silicate.  The 
water,  which  is  boiled  for  a long  time  in  glass  vessels, 
becomes  alkaline  and  turbid  by  the  portion  of  earthy 
and  insoluble  silicates  ; it  is  also  very  marked  on 
crown,  plate  and  window-glass. 

It  is  well  known  that  looking-glasses  tarnish  some- 
times in  the  air,  likewise  optical  instruments,  owing 
to  a deposit  of  a film  of  hygrometrical  water.  The 
windows  of  houses,  offices  or  public  buildings  of  an 
old  date,  often  present  a tarnished  surface  from  the 
same  cause  stated  ; glass  tubes,  globes,  retorts,  watch- 
glasses,  when  exposed  to  moist  air,  exhibit  the  same 
phenomenon. 

Action  of  Alkalies. — Concentrated  solutions  of  all 
alkalies  attack  the  glasses  more  powerfully  than  moist 
air. 

Action  of  Acids. ^ — The  acids  act  on  glasses  with 
facility,  particularly  hydrofluoric  acid,  which  acts  in 
a peculiar  manner  ; the  other  acids  tend  to  decompose 
glass,  by  seizing  on  the  bases,  and  setting  the  silica 
free.  Among  the  bottle  glass,  many  resist  the  action 
of  wine,  and  are  powerfully  attacked  by  nitric,  hydro- 
chloric and  sulphuric  acids.  A bottle  glass,  rich  in 
alumina,  is  readily  attacked  by  acids.  Wines  contain- 
ing much  bi-tartrate  of  potassa,  so  quickly  attack 
glasses,  that  the  alteration  is  perceptible  in  a few 
weeks.  The  action  of  hydrofluoric  acid  is  such,  that 
it  transforms  the  silica  of  the  glass  into  water  and 
fluoride  of  silicium.  It  attacks  glass  rapidly,  and  this 
property  has  been  traced  to  account  to  etch  glass  in  a 


PHYSICAL  CHARACTER. 


279 


gaseous  or  liquid  state  ; the  gaseous  acid  produces 
opaque  traces,  and  the  liquid  acid  transparent  ones. 

The  ])liysiGal  characters  of  glass^  in  relation  to 
heat,  may  be  stated,  that  all  glass  is  fusible,  but  the 
temperature  for  different  kinds  are  different.  Oxide 
of  lead  or  a large  amount  of  alkaline  silicates  imparts 
more  ready  fusibility.  Borax  produces  a similar 
effect.  Bottle  glass,  containing  oxide  of  iron  and 
alumina  and  less  alkali,  is  more  difficult  of  fusion  than 
other  kinds.  When  melted  glass  is  cooled,  it  is 
perfectly  flexible,  and  plastic  through  a wide  range  of 
temperature,  before  it  becomes  cooled  to  rigidity. 
The  softer  kinds,  especially  flint  or  borax  glass,  when 
heated,  begin  to  be  plastic  before  a red  heat,  the 
others  at  higher  temperatures,  and  the  plasticity  of 
all  increases  up  to  perfect  fusion.  When  in  the  plastic 
state  two  pieces  will  unite  together  as  firmly  as  if 
they  were  melted  together.  Some  glasses  are  more 
mobile  than  others  when  in  fusion.  When  glass  is 
much  softened  by  heat,  it  may  be  readily  drawn  out 
into  rods  or  tubes,  or  if  passed  around  a revolving 
wheel,  into  minute  flexible  threads.  From  its  perfect 
mobility  when  fused,  it  may  be  cast  into  large  sheets, 
such  as  plate  glass  ; from  its  plasticity  below  fusion, 
it  may  be  moulded  into  any  form  by  a few  simple 
instruments,  or  by  a mould  of  a given  form  ; from  the 
firm  union  of  two  plastic  pieces  very  complex  forms 
are  attainable.  Glass  conducts  heat  so  imperfectly, 
that  the  end  of  a rod  heated  to  whiteness  may  be  held 
with  safety  by  the  hand  within  an  inch  or  two  of  the 
heated  end  ; while  this  property  is  available  for  some 
uses,  it  is  an  inconvenience  in  other  respects,  which 
demands  a remedy. 


280 


ART  OF  QLA0S  MAKING. 


When  a tumbler  or  other  vessel  of  thick  glass  is 
cooled  in  the  air,  if  it  does  not  fly  to  pieces  on  cooling, 
it  will  readilj^  do  so  by  dropping  in  a grain  of  sand 
or  minute  angular  piece  of  Hint,  while  it  may  be 
struck  a smart  blow  with  a wooden  mallet  or  other 
smooth  body. 

Prince  Kupert’s  drops  are  pear-shaped  pieces  of 
glass,  with  a long  thin  stem,  made  by  dropping  melted 
glass  into  water.  The  bulb  may  be  struck  without 
injury;  but  if  the  smallest  particle  of  the  stem  be 
broken  off,  the  whole  drop  flies  into  powder  with 
explosive  noise  and  violence.  These  efiects  are  due 
to  the  bad  conducting  power  of  glass,  combined  with 
the  cohesive  force  of  its  particles.  Glass  expands 
when  heated  and  contracts  on  cooling,  but  as  its 
particles  move  more  slowly  in  proportion  as  it  ap- 
proaches the  cold,  rigid  state,  the  rate  of  cooling  must 
be  very  slow  to  allow  the  particles  to  come  uniformly 
close  together.  If  suddenly  cooled  by  dropping 
melted  glass  into  water,  the  outside  assumes  the  rigid 
and  more  contracted  form,  while  the  interior  is  still 
soft  and  expanded,  from  the  bad  conducting  power  of 
the  glass.  When  thoroughly  cooled,  the  interior  must 
still  retain  the  expanded  state,  so  contrary  to  its 
cohesive  force  at  common  temperatures,  and  when  the 
cohesion  of  the  outer  layer  is  in  the  least  disturbed, 
as  by  a scratch  or  slight  fracture,  the  whole  of  the 
cohesive  force  exerts  its  power  to  fracture  the  whole 
mass.  These  facts  make  it  necessary  to  cool  more 
slowly  than  can  be  done  by  the  air,  and  give  rise  to 
the  annealing  process;  the  particles  of  the  interior 
and  exterior  have  then  time  to  arrange  themselves 
uniformly,  according  to  their  cohesive  force  at  each 


SOLUBLE  GLASS. 


281 


point  of  temperature,  until  they  become  perfectly 
rigid. 

When  transparent  glass  is  maintained  for  some  time 
at  a high  heat,  but  below  fusion,  it  becomes  opaque  or 
translucent,  fibrous  in  structure,  harder,  less  fusible, 
and  a better  conductor  of  heat  and  electricit}^ ; it  is 
so  much  harder  as  to  scratch  glass,  give  sparks  with 
steel,  and  will  bear  sudden  changes  of  temperature  like 
porcelain.  As  an  example,  we  have  the  famous  devit- 
rified  glass  as  first  prepared  by  Reaumur,  and  is  more 
a crystaline  glass,  in  distinction  of  ordinary  amor- 
phous glass ; common  bottle  or  window  glass  are  most 
readily  afiected.  Although  a portion  of  alkali  is  sublim- 
ed, yet  the  change  is  not  dependent  on  the  loss  nor  on 
the  presence  of  any  accidental  impurities  ; the  altera- 
tion is  wholly  molecular,  and  consists  in  a re-arrange- 
ment of  the  particles  in  a crystaline  form,  where  glass 
itself  is  entirely  amorphous. 

^ When  crystaline  glass  is  still  more  highly  heated, 
it  fuses,  and  then  on  cooling  has  the  properties  of 
amorphous  glass,  but  requires  a little  higher  heat  for 
fusion,  after  each  molecular  change,  which  is  due  to 
loss  of  alkali. 

The  different  kinds  of  glass  have  different  degrees 
of  hardness  ; bottle  glass  being  the  hardest,  from  the 
quantity  of  oxide  of  iron  and  alumina,  and  the  smaller 
amount  of  alkali.  Lead  glass  is  softer  and  softer  in 
proportion  to  the  extent  of  oxide  of  lead ; an  excess  of 
alkali  imparts  greater  softness ; the  surface  of  the  glass 
appears  to  be  harder  than  the  interior.  Quartz,  other 
hard  minerals  and  a steel  file  scratch  glass  readily, 
and  the  diamond  is  generally  employed,  from  its  supe- 
rior hardness,  to  cut  the  glass.  The  curved  facets  of 


2S2 


ART  or  GLASS  MAKING. 


the  diamond  crystal  present  also  curved  edges,  and 
while  the  point  barely  enters  the  glass,  the  curved 
edges  or  shoulders  act  like  a wedge  to  split  the  glass. 
Glass  is  very  elastic,  as  may  be  shown  by  any  strip  of 
window  glass,  but  more  strikingly  by  hollow  balls 
suspended  by  strings.  The  ring  or  sound  emitted  by 
glass  on  being  struck  is  dependent  on  its  elasticity. 
A glass  harmonicon  consists  of  small  strips  of  window 
glass  of  different  sizes,  suspended  on  two  parallel 
strings,  and  may  be  graduated  to  any  scale.  Goblets 
of  various  sizes  are  sometimes  employed  in  a similar 
manner,  and  are  made  to  vibrate,  by  passing  the 
moistened  finger  around  their  upper  edges. 

The  discovery  of  glass  is,  without  contradiction,  one 
of  the  most  important  discoveries  which  accident  or 
chemistry  has  rendered  to  civilization.  Aside  from  its 
economical  uses,  it  has  exerted  a singular  infiuence  on 
the  progress  of  science.  It  is  chiefiy  by  this  aid  that 
astronomy  has  attained  a perfection  so  wonderful.  By 
the  aid  of  the  misroscope  naturalists  have  been 
enabled  to  study  a host  of  phenomena,  which  hitherto 
escaped  their  notice ; the  chemists  could  not  perform 
any  experiments  without  its  use ; and  to  glass  we  owe 
chiefiy  the  present  advanced  state  of  the  sciences,  so 
fruitful  in  marvelous  applications.  The  use  of  glass 
in  our  windows  has  introduced  a degree  of  comfort 
into  the  meanest  dwelling  which  previously  did  not 
appertain  to  the  costliest  palace.  By  means  of  the 
glass,  the  light  is  filtered  from  the  wind,  the  rain  and 
the  cold ; the  one  can  be  enjoyed  without  being  incon- 
venienced by  the  other.  With  the  improved  methods 
of  warming  we  can  create  an  indoor  climate,  adapted 
to  the  desires  and  feelings  of  the  dwellers.  The  em- 


HISTORY  OF  GLASS  MAKING. 


283 


ploymeiit  of  glass  in  many  domestic  articles  of  furni- 
ture contributes  to  cleanliness  and  health.  A clean 
glass  or  decanter,  water  and  other  liquids,  are  physi- 
cally tested  by  the  glass.  Glass,  which  is  so  extensively 
applied  and  used  to  so  many  purposes,  has  never  been 
the  subject  of  investigation  in  order  to  establish  the 
theory  of  its  combination. 

The  actual  definition  of  glass  is,  that  it  is  produced 
by  the  igneous  fusion  of  silicious  earth  with  certain 
alkaline  earths  or  salts,  or  with  metallic  oxides.  It  is 
most  probable  that  the  name  glass  is  derived  from  the 
latin  w”ord  glades;  ice  ; its  resemblance  to  it  has 
probably  suggested  its  title. 

The  art  of  blowing  glass  into  bottles,  making  it 
into  vases,  tinging  it  to  imitate  precious  stones,  melt- 
ing it  in  huge  masses  to  make  pillars,  polishing  it  into 
mirrors,  and  staining  it  in  part,  was  perfectly  known 
in  the  most  remote  ages.  Pliny’s  definition,  that  glass 
was  discovered  by  some  Phenician  soda  merchants, 
who  ha,ving  landed  on  the  banks  of  the  river  Belus, 
served  themselves  with  blocks  of  soda,  which  melting 
with  the  heat,  transformed  the  sand  on  which  they 
rested  into  glass,  is  very  problematic,  for  it  is  well 
known  what  temperature  is  required  for  making  glass. 
The  Bible  has  reference  to  glass,  and  the  Hebrews 
must  have  been  acquainted  with  it  while  in  Egypt. 
The  Portland  vase,  which  was  composed  of  a deep 
azure  glass,  with  figures  of  a delicate  white  opaque 
substance,  raised  in  relief,  was  found  in  the  tomb  of 
Alexander  Severus.  It  leaves  no  doubt  that  the  art 
of  glass  making  dates  3,500  years.  The  knowledge  of 
glass  making  was  .transferred  from  Egypt  to  Greece, 
thence  to  Rome  and  modern  Europe.  The  introduc- 


284  ART  OF  GLASS  MAKING. 

tion  into  Italy  was  made  by  the  Eomans  after  their  con- 
quests ; into  Asia,  at  the  time  of  Cicero.  Glass  beads 
and  amulets,  and  the  art  of  glass  making  was  known 
in  Britain  before  its  invasion  by  the  Eomans.  The 
glain  neidyr,  or  Druidical  glass  rings,  half  as  wide  as 
our  finger  rings,  but  much  thicker,  have  frequently 
been  found ; and  a superstition  regarding  them  ex- 
isted, that  they  were  produced  by  snakes  joining 
their  heads  together  and  hissing ; and  success  was 
thought  to  attend  any  one  who  was  fortunate  enough 
to  find  one  of  these  snake  stones  ; they  were,  evidently, 
beads  of  glass  employed  by  the  Druids,  under  the 
name  of  charms,  to  deceive  the  vulgar ; they  are, 
usually,  of  a green  hue,  but  some  of  them  are  blue, 
and  others  variegated  with  wavy  streaks  of  blue,  red 
and  white. 

In  Herculaneum,  glass  utensils  have  been  found 
which  date  back  to  its  destruction  by  the  eruption  of 
Mount  Vesuvius,  during  the  reign  of  Titus  ; two  panes 
of  glass  were  found  in  a window  at  Herculaneum.  In 
the  year  220,  a manufactory  of  glass  was  established 
in  Eome.  In  the  year  674,  window  glass  was  intro- 
duced in  England,  but  for  several  centuries  the  use  of 
window  glass  was  exclusively  confined  to  buildings 
appropriated  to  religious  purposes,  while  the  windows 
of  houses  were  filled  with  oiled  paper  and  wooden 
lattices.  The  skill  of  the  Venetians  in  glass  making 
was  especially  remarkable  in  the  excellence  of  their 
mirrors,  while  plates  of  polished  metal  were  used  at 
the  toilet  in  other  countries.  France  began  to  manu- 
facture glass  in  the  fourteenth  century  ; but  not  until 
the  year  1701,  did  success  attend  its  manufacture, 
under  the  direction  of  D’Agincourt.  In  the  year  1557 


HISTORY  OF  GLASS  MAKING. 


285 


the  manufacture  of  window  glass  was  commenced  in 
England,  and  Yenetian  workmen  were  employed  by 
the  duke  of  Buckingham  in  1670  at  Lambeth,  London. 
The  first  painted  glass  was  executed  in  England 
during  the  time  of  King  John.  The  Keformation 
greatly  impeded  the  progress  of  the  art;  it  nearly 
disappeared  during  the  reign  of  Queen  Elizabeth.  A 
glass  painter,  named  William  Price,  is  said  to  have 
discovered  and  kept  secret  the  art  of  glass  staining, 
and  to  produce  a rich,  clear,  bright  and  transparent  red. 

In  the  United  States  the  manufacture  of  glass  dates 
as  far  back  as  1790,  by  Eobert  Hews,  a citizen  of  Boston, 
who  erected  his  factory  in  Hew-Hampshire  for  making 
window  glass ; in  1800  another  manufactory  was 
established  in  Boston.  The  manufacture  of  flint  glass 
originated  in  the  Eastern  States,  and  Hew- York  and 
Pennsylvania  followed  it  up,  so  that  there  are  now  at 
the  present  day  110  manufactories  of  flint  and  green 
glass,  and  3>J  manufactories  of  window  glass  and 
lamp  shades,  consuming  as  follows : 


Coal,  over  - 

100,000 

tons. 

Sand,  - - - 

10,000 

iC 

Lead,  - - - ‘ - 

5,000 

u 

Soda  ash,  - . - 

6,000 

u 

Nitrate  of  soda. 

3,000 

u 

Bicarbonate  of  soda. 

1,000 

u 

Binoxide  of  manganese, 

200 

u 

Coloring  materials  for  buttons 

and 

ladies’  ornaments,  such  as  zafire, 

cobalt,  oxides  of  copper,  tin. 

anti- 

mony,  chrome,  uranium,  &c.. 

10 

ii 

White  arsenic. 

20 

u 

13* 


28G 


ART  OF  GLASS  MAKING. 


The  City  of  Pittsburgh  contains  the  largest  number 
of  glass  manufactories,  on  account  of  the  cheapness 
of  materials,  such  as  coal  and  sand,  which  is  at  their 
command  ; there  are  no  less  than  65  establishments 
for  producing  window,  flint  and  bottle  glass,  20  bottle 
and  vial,  23  window  glass  factories,  and  a number  of 
glass  factories  whose  exclusive  production  consists  of 
lamp  chimneys,  and  one-half  of  the  glass  manufactured 
in  the  United  States.  Pennsylvania  claims  two-thirds 
of  the  entire  production  of  the  United  States.  Pitts- 
burgh consumes  four  millions  of  bushels  of  soft  coal, 
and  upwards  of  three  thousand  tons  of  soda  ash 
annually  ; employs  nearly  five  thousand  hands,  who 
receive  three  millions  of  dollars  in  wages.  The  im- 
provements in  making  the  glass  are  far  advanced  ; 
when  formerly  200  feet  of  glass  were  made  by  a 
blower  at  a single  blowing,  now  there  are  800  feet 
made  ; 8 x 10  was  the  largest  size  manufactured,  now 
they  are  40  x 70  ; formerly  the  thickness  of  the  sheets 
averaged  18  to  the  inch,  now  they  average  12,  single 
strength  ; their  present  double  strength  is  about  one- 
eighth  inch  thick. 

McCully  & Co.,  manufacturers  of  green  glass  bottles, 
supply  a proprietor  of  stomach  bitters  with  1,000  gross 
per  month.  There  are  a number  of  glass  stainers  con- 
stantly engaged  there  for  steamboat  furniture.  The 
capital  invested  there  is  five  millions  of  dollars. 

In  JMew-York  State  there  are  about  12  glass  facto- 
ries, in  Massachusetts,  10. 

The  Specific  Gravity  of  Different  Kinds  of  Glass. 

It  may  be  of  some  importance  to  know  the  specific 


SPECIFIC  GEAVITT. 


257 


gravity  of  glass,  as  it  depeads  on  the  component  parts. 
Alkaline  calcareous  glasses  are  the  lightest;  bottle 
glass  comes  next,  then  plumbiferous  glasses,  and  the 
following  table : 


Bohemian  glass,  spec,  grav.,  2.396 

Crown  glass,  “ 2.487 

French  plate  glass,  “ 2.48S 

Window  glass,  ‘‘  2.642 

Bottle  glass,  “ 2.732 

Crystal,  or  common  dint  glass  “ from  2.9  to  3.255 

Optical  dint  glass,  “ “ 3.3  to  3.6 

White  dint  glass,  “ , 3.000 

Common  green  bottle  glass,  2.715 

St.  Helen’s  green  glass,  “ 2.654 

Crown  glass,  “ 2.520 

Leith  Crystal,  3.189 

English  Plate  glass,  “ 2.439 


As  regards  crystal  or  dint  glass,  the  density  may 
sufdce  to  givm  a pretty  exact  idea  of  its  composition  ; 
it  is,  however,  not  so  with  the  other  kinds  of  glass,  the 
difference  of  density  of  their  constituents  not  being 
sufficiently  marked  ; for  the  relations  vary  from  so 
many  causes,  that  to  establish  them  in  a positive 
manner  it  would  be  necessary  to  limit  oneself  to 
certain  glasses,  and  it  would  therefore  be  best  to  have 
recourse  to  a chemical  analysis,  the  result  of  which 
will  always  be  more  reliable. 


TREATISE  ON  SOAP  MAKING, 

THE  ART  OP  ITS  MANUFACTURE,  WITH  AND  WITHOUT  THE  AID 
OF  SILICATES,  AND  DESCRIPTION  OP  ALL  KINDS  OF  HARD, 

SOFT  AND  TOILET  SOAPS  ; WITH  TABLES  OP  THE 
COMPOSITION  OF  THE  YARIOUS  MANUFACTU- 
RERS, ETC.,  ETC.,  ETC. 

By  Dr.  LEWIS  FEUCHTWAI^GER. 

Soap  is  a compound  of  salifiable  bases  with  all  fats 
and  oils.  When  fats  and  oils  undergo  saponification 
by  reaction  with  a salifiable  base,  the  three  principles 
contained  in  them,  such  as  stearin^  margarin  and 
olein^  are  decomposed  into  oily  acids  peculiar  to  each, 
as  discovered  by  Chevreul,  a celebrated  French  chem- 
ist, in  1811,  and  called  by  him  stearic,  margaric  and 
oleic  acids,  which  unite  with  the  base  to  form  the 
soap,  and  a sweet  principle,  not  saponifiable,  called 
glycerin^  which  is  set  free ; so  that  stearin  is  a stearate, 
margarin,  a margarate,  and  olein  an  oleate  of  glycerin. 
Oils  are  mixtures  of  these  three  oily  salts,  and  soaps 
are  mixed  stearates,  margarates  and  oleates  of  various 
base. 

Steario  acid  is  a firm  white  solid,  like  wax,  fusible 
at  167°,  greasy  to  the  touch,  pulverizable,  soluble  in 
alcohol,  very  soluble  in  ether,  but  insoluble  in  water ; 
it  is  used  as  a substitute  for  wax  in  making  candles. 
Margaric  acid  has  the  appearance  of  fat  or  hog’s  lard, 
which  is  fusible  at  140°.  Oleic  acid  is  an  oily  liquid, 
insoluble  in  water,  soluble  in  alcohol  and  ether. 


SOAP  MAKING. 


289 


lighter  than  water,  crystalizable  in  needles  at  a tem- 
perature below  32°,  and  having  a slight  smell  and 
pungent  taste.  Glycerin,  the  product  of  the  decomposi- 
tion, is  a thick  syrupy  liquid,  either  colorless  or  of  a 
slight  amber  color,  without  smell  when  pure,  unctuous 
to  the  touch,  and  of  a very  sweet  taste. 

There  are  soluble  and  insoluble  soaps  ; the  soluble 
are  combinations  of  the  oily  acids  with  soda,  potassa 
and  ammonia  ; the  insoluble  consist  of  the  same  acids, 
united  with  earth  and  metallic  oxides.  The  soluble 
soaps  are  only  used  as  detergents,  and  are  properly 
named  soaps,  while  the  insoluble  soaps  are  emploj^ed 
in  medicine,  such  as,  for  example,  the  lead  plaster,  and 
liniments. 

Soaps  are  mostly  divided  in  hard  or  soft  soaps ; the 
consistency  of  the  fixed  alkaline  soaps  depends  partly 
on  the  nature  of  the  oil  or  fat,  and  partly  on  the 
alkali  present.  Soaps  are  harder  the  more  stea- 
rate and  margarate  they  contain,  and  softer  when 
the  oleate  predominates.  The  alkalies  have,  likewise, 
a different  effect  upon  their  consistency  ; they  are 
harder  when  formed  with  soda,  and  softer  when  con- 
taining potassa ; the  pure  soaps  are  generally  the 
hardest  and  least  soluble,  while  oleate  of  potassa  is  the 
softest  and  most  soluble.  Mutton  suet,  beef  tallow 
and  hog’s  lard  contain  mostly  stearin e and  margarine, 
but  also  olein  ; butters  and  other  suets  contain  buty- 
rine  or  butyric  acid.  A great  many  vegetable  and 
animal  substances  contain  either  one  or  the  other  of 
the  above  or  allied  acids,  and  are  converted  into  soaps 
by  their  combinations  with  any  alkalies  or  alkaline 
earths,  and  receive  thus  the  name  from  the  substances 
they  are  originating;  such  as  we  have  a cocoanut  oil 


290 


SOAP  MAKING. 


soap,  the  product  of  cocoanut  oil  with  lime ; wax  soap, 
made  in  the  same  manner. 

Soaj^^  and  the  art  of  manufacturing  it,  has  been 
known  to  the  ancients ; the  Romans  followed  it  as  a 
branch  of  industry,  for  they  knew  well  how  to  use 
many  vegetables  possessing  detergent  properties,  as 
also  the  virtues  of  alkalies,  such  as  soda  and  kousa,  a 
potash  lye  for  similar  purposes.  Italy  and  Spain, 
in  the  eighth  century,  first  established  soap  manufac- 
tories, and  in  the  thirteenth  century  France  followed 
up  this  trade ; and  Marseilles  began  to  manufacture 
the  oil  soap,  having  learnt  to  extract  the  oil  from 
olives,  which  were  abundantly  cultivated  there,  and 
to  combine  the  same  with  the  ashes  of  their  algae, 
thrown  out  from  the  Mediterranean  Sea.  England, 
in  the  sixteenth  century,  followed  up  the  French 
method,  but  in  place  of  the  olive  oil,  employed  tallow, 
in  connection  with  potashes  and  salt. 

In  later  years,  the  English  tallow  chandler,  or  soap 
maker,  conceived  many  improvements  in  his  trade, 
by  the  introduction  of  rosin  into  his  soap,  which  gave 
it  many  decided  advantages.  The  great  analytical 
chemist,  Chevreul,  among  his  many  discoveries, 
studied  the  proximate  principles,  and  made  his  in- 
vestigations known  in  1811,  and  produced  quite  a 
revolution  in  this  domestic  art ; and  from  that  period 
many  new  inventions  and  improvements  have  been 
introduced — both  the  machinery  and  application  of 
heat ; for  no  soap  can  be  produced  without  the  proper 
heat,  whether  by  direct  fire,  as  formerly,  or  by  or- 
dinary or  superheated  steam,  as  at  present  practiced ; 
also,  the  various  ingredients,  like  the  caustic  soda, 
where  formerly  barilla  and  soda  ash  were  entirely  used ; 


60AP  MAKING. 


291 


also,  the  time  which  was  formerly  wasted  in  prodnc* 
iiig  soap,  all  of  which  form  the  improvements  of  the 
day  in  the  manufacture  of  soap.  The  present  soap 
maker  operates  systematically,  uses  his  alkalimeter, 
in  order  to  test  the  strength  of  his  lye,  and  his  ther» 
mometer,  in  order  to  hit  the  proper  temperature  when 
the  heat  required  for  saponification  should  be  pro- 
duced, and  measures  the  exact  time  when  to  abstract 
the  heat  and  wdien  to  cool  the  mixture. 

Before  proceeding  to  the  manufacture  of  the  various 
soaps,  it  is  indispensable  to  state  the  different  vehicles 
used  in  the  process,  the  alkalies  and  lyes  required  for 
the  saponification  of  fats,  grease  and  oils.  The  appa- 
ratus used  for  boiling  soaps  consists  in  l)riclc  kettles^ 
because  they  retain  longest  the  heat  during  the  opera- 
tion ; the  foiling  pan^  the  upper  part  of  which,  con- 
sisting of  a wooden  curb  fastened  into  the  rim  of  the 
boiler,  is  now  in  general  use,  for  the  reason,  as  ample 
space  is  required  for  the  soap  paste  to  froth  upwards, 
wdien  superheated  steam  is  employed.  They  are  only 
used  in  large  factories,  wdiere  from  100,000  to  130,000 
pounds  are  weekly  manufactured. 

Cast  iron  kettles  are  found  at  present  in  small 
factories,  also  the  sheet  iron  kettles,  which  have  the 
preference  over  cast  iron  kettles.  When  the  manu- 
facture is  conducted  in  open  fire,  common  kettles 
must  be  so  constructed  as  only  the  bottom  undergoes 
the  greatest  heat,  and  not  on  the  sides. 

Superheated  steam  is  now,  however,  the  only  appa- 
ratus in  the  manufacture  of  soaps,  at  the  boiling  point 
temperature,  when  the  heat  is  introduced  directly  into 
the  material,  while  ordinary  steam  would  have  to  be 
condensed  through  a worm,  and  the  condensed  vapor 


292 


SOAP  MAKING. 


then  to  be  discharged,  and  both  time  and  fuel  are 
much  economized.  Improvements  are  now  continually 
made,  both  in  machinery  and  materials.  An  appa- 
ratus, called  Hubert’s,  where  two  boilers  are  employed 
instead  of  one,  as  usual,  in  connection  with  super- 
heated steam,  and  when  the  lye  and  fat  are  introduced 
in  both  vats,  steam  in  a superheated  state  is  intro- 
duced, and  injected  into  the  entire  mass. 

The  steam  jacket  is  also  a late  improvement,  for  the 
purpose  of  mixing  and  boiling  of  the  soap  ingredients 
simultaneously. 

The  Alkalies. 

Potassa,  either  the  crude,  or  jpearl  ashes,  are  both, 
but  mostly  the  latter,  at  present  employed  for  cer- 
tain soaps.  The  first  is  also  called  potash  or  caustic 
potassa,  and  contains  but  60  per  cent,  absolute  alkali, 
while  pearl  ashes  contain  50  per  cent,  of  pure  alkali ; 
the  balance  consists  in  sulphate  and  chloride  potas- 
sium, phosphate  and  silicate  of  lime  and  other  impu- 
rities, such  as  organic  matter,  .free  silex  and  lime,  &c., 
&c.  The  pot  and  pearl  ashes  are  used  in  producing 
soft  soaps  or  fancy  soaps,  for  the  reason  they  do  not 
produce  such  hard  materials  which  the  soda  com- 
pounds do.  In  former  times  potash,  mostly  in  caustic 
condition,  was  employed  in  soap  making,  and  by  the 
addition  of  salt,  the  soap  was  made  hard  ; at  present, 
however,  potash  or  pearl  ashes  are  mostly  discarded 
in  soap  making. 

Soda,  in  the  form  of  caustic  soda,  soda  ash  and  sal 
soda,  are  all  now  exclusively  used  in  soap  making. 
Barilla,  which  is  the  crude  soda  obtained  from  the 
incineration  of  the  kelp,  is  still  used  by  some  old  soap 


THE  ALKALIES, 


293 


makers  in  place  of  the  caustic  soda ; there  is  also  a 
natural  soda,  called  urao,  used  in  South  America, 
which  is  purer  than  barilla,  on  an  average  containing 
but  25  per  cent.  ; the  same  is,  however,  still  in  much 
use  by  the  Spanish  manufacturers,  who  bring  the 
same  in  large  quantities  to  England.  The  manufac- 
ture of  soda  ash,  as  obtained  from  salt,  and  transforma- 
tion into  crude  carbonate  of  soda,  under  the  name  of 
hlack  ash^  its  purification  by  lixiviation,  evaporation 
and  calcination,  then  assuming  the  name  of  soda  ash 
or  white  ash^  is  the  process  pursued  in  England. 
Eighty  per  cent,  carbonate  of  soda  is  the  mercantile 
standard  corresponding  with  the  English  per  centage 
of  48  per  cent. ; 100  parts  consist  in  36  parts  car- 
bonate of  soda,  and  64  parts  in  water  of  crystalization. 

Caustic  soda^  which  is  now  exclusively  used  by  soap 
makers,  is  generally  purer  and  more  caustic  than  the 
last  mentioned  alkali ; it  does  not,  however,  bear  much 
exposure,  as  it  absorbs  moisture  from  the  atmosphere, 
and  becomes  fiuid  unless  soon  used,  and  is  accom- 
panied by  a loss  of  material,  but  it  is  more  certain 
and  easier  for  operating  on  the  materials. 

Sal  soda  or  soda  crystals  form  a very  important 
adjunct  in  soap  making  ; they  are  mostly  added  after 
saponification  has  taken  place,  and  for  finishing  by 
the  operation  called  filling  the  soap.  They  are 
obtained  by  dissolving  soda  ash  in  ten  times  as  much 
hot  water,  and  allowing  them  to  crystalize  ; they  are 
used  for  softening  the  water  and  washing  purposes. 
In  nature  the  carbonate  of  soda  is  found  in  many 
countries  as  an  efflorescence  on  the  soil  and  in  the 
beds  of  dried  up  lakes.  The  writer  saw  some  years 
ago  in  Nevada  large  districts  of  land  covered  with  a 


294 


SOAP  MAKING. 


white  crust  which  was  proved  to  be  the  carbonate  of 
soda.  In  Carson  valley  miles  of  this  alkali  are  spread 
over  the  surface. 

Carbonate  of  soda  has  latterly  been  extracted  from 
the  Greenland  mineral,  called  cryolite,  which  is 
largely  exported  from  that  country ; it  is  extracted 
from  cryolite  by  lixiviation,  and  carbonic  acid  passed 
through  the  solution,  and  the  carbonate  of  soda  left 
to  crystalize.  Cryolite,  when  mechanically  cleaned 
and  deprived  of  foreign  substances,  is  employed  in  the 
manufacture  of  soap;  it  consists  in  100  parts,  of  13 
alumina,  34  soda,  and  54  fluorine,  30  by  using  the 
native  minerals  ; it  is  used  for  Ailing  in. 

To  TEST  THE  STEENGTH  OF  AN  AlKALI. 

In  order  to  ascertain  the  quality  and  strength  of 
the  alkali  used  in  the  manufacture  of  soap,  it  will  re- 
quire a thorough  chemical  knowledge,  which  cannot 
be  expected  from  a soap  maker  ; but  as  it  is  of  the  high- 
est importance  to  guard  against  imposition,  and  in  the 
preparation  of  his  lye,  to  learn  the  exact  proportions 
for  adding  to  the  alkalies,  it  is  necessary  to  give  some 
short  instruction  on  the  subject. 

The  following  points  must  be  observed  in  the  pur- 
chase of  caustic  soda,  soda  ash  and  potassa : 1.  The 
water  which  is  frequently  left  in  the  alkalies  in  order 
to  increase  the  weight;  2.  To  estimate  the  amount 
of  caustic  and  carbonated  alkali.  By  heating  100 
grains  of  the  alkali  over  a gas  lamp  in  an  iron  ladle 
for  a short  time,  until  all  water  is  expelled,  which  can 
be  ascertained  by  holding  a cold  glass  plate  for  a mo- 
ment over  the  ladle,  when  whatever  vapor  arises  from 


STEENGTH  OF  AN  ALKALI. 


295 


the  heated  material  will  be  condensed  on  its  surface ; 
the  net  weight  will  indicate  the  amount  of  water  in 
the  above  quantity. 

As  all  alkalies  are  used  in  a caustic  state,  so  it  re- 
quires its  estimation,  which  is  done  by  treating  fifty 
grains  of  commercial  soda,  finely  ground,  with  half  an 
ounce  of  strongest  alcohol  in  a porcelain  capsule  ; 
shake  them  well  together,  decant  the  liquid,  and 
evaporate  it  quickly  until  it  has  become  quite  dry  ; 
weigh  when  cool,  and  ascertain  the  actual  amount  of 
caustic  soda  which  the  fifty  grains  at  first  used  have 
lost ; it  is  understood  that  you  have  tared  the  porce- 
lain dish  with  the  sample  of  soda,  and  that  you  deduct 
afterwards  the  weight  of  said  dish,  as  soon  as  the 
operation  is  completed ; now  twenty  grains  loss  would 
make  the  loss  forty  grains  on  one  hundred  grains  of 
the  sample.  In  order  to  estimate  the  amount  of  car- 
bonated alkali,  it  is  indispensable  to  ascertain  first  the 
quantity  of  either  soda  or  potash,  and  then  convert  by 
calculation  the  value  of  the  carbonated,  which  is  done 
by  dissolving  fifty  grains  in  a flask  containing  two 
ounces  of  water  ; then  add  from  one  hundred  grains 
finely  powdered  oxalic  acid  to  the  alkaline  solution  so 
long,  until  a little  strip  of  litmus  paper  becomes 
slightly  reddened,  the  liquid  being  kept  hot.  The 
residue  of  the  oxalic  is  then  weighed,  and  the  loss 
ascertained  ; if  the  loss  is  forty-three  grains,  then  fifty- 
seven  grains  were  consumed  in  the  neutralization  ; it 
is  known  that  7.87  grains  of  oxalic  acid  are  capable  of 
saturating  five  grains  of  caustic  soda,  or  seven  grains 
of  caustic  potassa ; five  grains  of  caustic  soda  are 
equivalent  to  6.62  grs.  of  carbonate  of  soda,  and  seven 
grains  of  caustic  potassa  are  equivalent  to  8.63  car- 


296 


SOAP  MAKING. 


bonate  of  potassa;  16.2  grains  caustic  soda  are  now 
equivalent  to  21.5  grains  of  carbonate  of  soda,  which, 
when  doubled,  gives  the  quotient  of  forty-three  per 
cent.  As  we  have  found  10  per  cent,  water,  40  per 
cent,  caustic  soda,  and  43  per  cent,  carbonate  of  soda, 
the  balance  of  the  one  hundred  grains  soda  ash  must 
be  seven  grains  as  foreign  substance. 

For  ascertaining  the  nature  of  foreign  substances 
contained  in  a soda  ash,  such  as  a chloride  or  a sulphate, 
more  chemical  knowledge  is  required  ; but  a few  drops 
of  nitrate  of  silver  added  to  a clear  solution  of  the 
suspected  sample,  which  has  been  a little  acidulated 
by  nitric  or  sulphuric  acid,  will  at  once  prove  the 
presence  of  salt,  which  is  chloride  of  sodium,  or  of  a 
chloride  of  potassium,  by  a white  flocky  precipitate 
being  formed  ; a sulphate  may  be  detected  by  first 
neutralizing  the  solution  of  the  suspected  sample  with 
a few  drops  of  nitric,  and  then  adding  a few  drops  of 
chloride  of  barium,  whereby  a fine  heavy  white  pre- 
cipitate is  formed. 

The  Alkalies  are  made  into  Lyes. 

The  soft  waters,  and  those  from  rivers  and  springs, 
and  free  from  organic  matters,  ought  only  to  be  used 
for  the  preparation  of  lyes. 

Under  the  word  lye,  we  understand  the  aqueous 
solution  of  caustic  soda,  or  potassa,  prepared  from  the 
common  soda  ash,  or  the  crystals  of  soda,  which  are 
converted  into  the  caustic  state  by  means  of  lime-water, 
whereby  the  carbonic  acid  of  the  alkalies  unite  with 
the  lime,  forming  insoluble  carbonate  of  lime,  which 
settles  at  the  bottom ; the  whole  operation  is  per- 


MAKING  ALKALI  INTO  LYE. 


297 


formed  in  a large  kettle  containing  hot  water.  The 
caustic  state  of  the  Ije  is  ascertained  by  taking  out  a 
few  drops,  which  must  not  effervesce  with  any  acid ; if 
found  neutral,  the  lye  is  left  to  settle  for  twelve  or 
fifteen  hours  before  using  it  in  the  soap  kettle ; the 
lime  required  for  the  lye  must  be  the  fat  lime,  and 
twenty-four  pounds  of  quick-lime  are  requisite  for  one 
hundred  pounds  of  crystalized  soda,  while  sixty 
pounds  of  fat  lime  are  required  for  one  hundred  pounds 
of  soda  ash.  If  pearl  ashes  are  intended  for  producing 
a lye,  forty-eight  pounds  of  fat  lime  are  necessary  for 
one  hundred  pounds  of  pearl  ashes  ; an  excess  of  lime 
does  not  produce  an  injury  to  the  lye. 

The  strength  of  the  lye  must  be  ascertained  by 
Baume’s  hydrometer,  which,  however,  only  indicates 
the  relative  strength  of  the  lye,  with  all  impurities, 
yet  is  a sufficient  guide  for  making  it  into  soap.  The 
following  table  exhibits  the  quantity  of  fused  potassa 
and  solid  caustic  soda  in  one  hundred  parts  of  lye,  with 
their  respective  degrees,  after  Baume’s  hydrometer : 


j Degrees. 

1 

Specific  Gravity. 

Potassa  in  100. 

Soda  in  100. 

1 

40° 

1.357 

33.46 

32.40 

35° 

1.299 

29.34 

28.16 

30° 

1.245 

24.77 

22.58 

25° 

1.196 

20.30 

17.71 

20° 

1.151 

16,40 

13.77 

18° 

1.134 

14.38 

12. 

1 16° 

1.117 

12.29 

10.26 

14° 

1.101 

10.59 

8.85 

12° 

1.085 

9.20 

7.69 

10° 

1.070 

7.74 

6.49 

8° 

1.055 

6.25 

5.46 

6° 

1.041 

4.77 

4.02 

4° 

1,027 

3.21 

2.92 

2° 

1.013 

1.63 

1.38 

0° 

1.000 

— 

— 

298 


SOAP  MAKIKG. 


In  certain  cases,  it  is  requisite  to  transform  stronger 
lyes  into  weaker  of  a definite  degree  of  strength. 
Though,  to  effect  this,  much  precision  is  needed  ; still, 
we  think  the  reader  will  find  little,  if  any  difficulty, 
after  perusing  the  annexed  part,  containing  four  tables 
for  the  reduction  of  strong  lyes,  published  by  Mr.  Eu- 
gene Lorrne,  the  excellent  author  of  the  work  “ Manuel 
complet  du  Savonnier.’^ 

The  first  column  at  the  left  of  each  table  shows  the 
quantity  and  the  degree  of  the  lye  to  be  diluted. 

The  second  indicates  the  quantity  of  water  to  be 
added  to  the  lye. 

The  third  gives  the  amount  of  the  lye  obtained  by 
the  admixture  of  both  liquids ; and 

The  fourth  exhibits  the  areometric  degree  of  the  lye. 

TABLE  I. 


Showing  the  different  areometric  degrees  resulting  from  a mixture 
of  10  gallons  of  soda  lye,  of  36  degrees^ Baume,  with  quantities  of 
water  mrying  from  10  to  60  gallons. 


Number 
of  gallons  of  Lye 
of  36  degrees. 

Number 

of 

gallons  of  Water. 

Number 
of  gallons  of 
obtained  Lye. 

Areometric 
degree 
of  the  Lye. 

10 

10 

20 

23 

10 

20 

30 

17 

10 

30 

40 

14 

10 

40 

50 

12 

10 

50 

60 

10 

10 

60 

70 

9 

10 

70 

80 

8 

10 

80 

90 

10 

90 

100 

6i 

10  gallons  of  lye,  of  36  degrees  Baume,  weigh  112^  lbs. 

TABULAR  STATEMENT. 


299 


TABLE  II. 


Showing  the  different  areometric  degrees  resulting  fro7n  a mixture 
ofV)  lbs.  of  soda  lye,  of  36  degrees  Baume,  with  quantities  of  water 
varying  from  10  to  100  lbs. 


NumlDer 

of  pounds  of  Lyel 
of  36  degrees. 

NumlDer  of 
pounds  of  Water 
to  be  employed. 

Number 
of  pounds  of 
Lye  obtained. 

Areometric 
degree 
of  the  Lye. 

10 

10 

20 

21 

10 

20 

30 

14i 

10 

30 

40 

Hi 

10 

40 

50 

10 

10 

50 

60 

9 

10 

60 

70 

8 

10 

70 

80 

10 

80 

90 

4i 

10 

90 

100 

5 nearly. 

8.8  gallons  of  lye,  of  40  degrees  Baume,  weigh  lOO  lbs. 


TABLE  III. 


Showing  the  different  areometric  degrees  resulting  from  a mixture 
of  10  gallons  of  soda  lye,  of  30  degrees  Baume,  with  quantities  of 
water  varying  from  10  to  90  gallons. 


Number 
of  gallons  of 
Lye  of  30  degrees. 

Number  of 
gallons  of  Water 
to  be  employed. 

Number 
of  gallons  of 
Lye  obtained. 

Areometric 
degree 
of  tbe  Lye. 

10 

10 

20 

19 

10 

20 

30 

nearly  14 

10 

30 

40 

11 

10 

40 

50 

9 

10 

50 

60 

8 

10 

60 

70 

7 

10 

70 

80 

6 

10 

80 

90 

5 

10 

90 

100 

4i 

Piemarks. — 10  gallons  of  soda  lye,  of  30  degrees,  weigh  100 
lbs  ; 75  gallons  of  this  lye,  and  25  gallons  of  water,  give  100 
gallons  of  lye  of  25  degrees  Baume.  There  are  23J  lbs.  of 
caustic  soda  wanted  for  making  10  gallons  of  lye  of  30  degrees 
Baume. 


300 


SOAP  MAKING. 


TABLE  IV. 


Showing  the  different  areometric  degrees  resulting  from  a mixture 
of  10  lbs.  of  soda  lye,  of  30  degrees  Baume,  with  quantities  of  water 
mrying  from  10  to  90  lbs. 


Number 
of  pounds  of 
Lye  of  30  degrees. 

Number  of 
pounds  of  Wateri 
to  be  employed. 

Number 
of  pounds  of 
Lye  obtained. 

Areometric 
degree 
of  the  Lye. 

10 

10 

20 

17 

10 

20 

30 

12 

10 

30 

40 

n 

10 

40 

50 

10 

50 

60 

6i 

10 

60 

70 

5i 

10 

70 

80 

5 or  5i 

10 

80 

90 

4i 

10 

90 

100 

4 

9.6  gallons  of  lye,  of  30  degrees  Baume,  weigh  100  pounds. 


The  saponifiable  oils  and  fats  for  the  mannfactnre 
of  all  kinds  of  soaps  are  from  the  vegetable  and  ani- 
mal kingdoms ; the  fats  or  fatty  acids  which,  as  already 
explained,  consist  of  margaric,  stearic  and  oleic  acids, 
in  combination  with  the  oxide  of  glyceril  in  various 
proportious,  we  find  the  margarin  principally  in  but- 
ters, and  not  drying  oils ; the  stearin  in  the  suets,  and 
the  olein  forms  the  liquid  portion  of  most  animal  and 
many  vegetable  fats  ; we  also  find  the  palmitin,  which 
bears  some  resemblance  to  stearine,  but  is  principally 
contained  in  palm  oil,  and  which  contains  the  acid  in 
a free  state,  (not  having  any  glycerin,)  and  for  this 
reason  possesses  many  advantages  over  other  similar 
substances  in  the  manufacture  of  soap.  Fats  contain 
also  animal  tissues,  albumen,  pigments,  and  frequently 
peculiar  acids,  and  thereby  producing  peculiar  odors. 


PALM  OIL. 


301 


of  wliicli  organic  chemistry  gives  hundreds  of  exam- 
ples. Mutton  fat  and  goose  grease  owe  their  peculiar 
strong  odor  to  another  acid,  called  hircine. 

The  vegetable  fats  or  oils  are  numerous  and  of 
different  consistencies ; they  are  all  lighter  than  water, 
of  a specific  gravity  of  0.9  to  0.919,  and  all  insoluble 
in  cold  and  hot  water,  easily  soluble  in  ether,  and  all 
possess  a sweet  taste  ; many  of  them  undergo  changes, 
some  solidify,  others  thicken  and  become  hard,  but 
retain  their  brilliancy  ; they  have  therefore  been  class- 
ified with  fluid  and  non-siccative  oils.  Linseed,  hemp- 
seed  and  poppy  oils  belong  to  the  first,  and  olive,  palm, 
sweet,  almond  and  cocoanut  oils  belong  to  the  latter 
class. 

Cocoanut  oil^  also  called  cocoanut  butter,  is  found 
in  a liquid  state  in  the  nut  of  some  palm  species  in 
the  southern  or  tropical  hemispheres,  such  as  Brazil, 
Ceylon  and  many  Pacific  States.  It  yields  60  per  cent, 
of  the  fatty  acid  ; it  is  white,  sweet,  and  of  the  con- 
sistency of  lard,  mild  taste  and  agreeable  odor  ; it 
melts  between  60°  and  70°  Fahr.,  and  becomes 
easily  rancid.  It  forms  hard  soaps,  although  it  sapon- 
ifies but  slowly,  and  is  therefore  mixed  with  either 
tallow  or  palm  oil,  both  of  which  are  improved 
thereby,  as  it  increases  in  emollient  properties,  and 
gives  a brilliant  whiteness  to  tallow  soap. 

Palm  Oil. — Several  varieties  of  palm  trees  yield 
the  fruit  containing  the  oil  or  butter.  South  America, 
Africa  and  the  East  Indies  are  the  localities  from 
where  the  extracted  oil  is  brouglit  to  this  country. 
The  color  of  palm  oil  varies  much,  according  to  several 
circumstances,  either  of  orange  or  even  of  violet. 

Palm  oil  is  prepared  from  the  fruit  of  the  palm 

II 


302 


SOAP  MAKING. 


tree  {Clceis  Qxiineensis)  as  follows : — On  its  arrival  at 
maturit}",  the  fruit  is  plucked  and  thrown  into  a heap 
on  the  ground,  where  it  is  left  for  about  a month. 
Fermentation  is  thus  produced.  When  this  is  suffi- 
ciently advanced,  the  mass  is  thrown  into  large  iron 
vats  and  boiled  with  water,  the  fruits  being  crushed 
in  the  hands  of  the  laborers  from  time  to  time.  After 
prolonged  boiling,  they  are  pounded  in  rude  mortars 
formed  from  the  trunks  of  trees,  the  kernels  are 
removed,  and  the  shells  again  boiled.  The  oil  then 
floats  on  the  surface  of  the  liquid,  and  is  collected 
with  large  wooden  spoons. 

Properties, — Palm  oil  is  solid  at  the  ordinary  tem- 
perature of  our  climates  ; its  color  is  a reddish  yellow, 
and  is  esteemed  in  proportion  to  the  deepness  of  its 
color.  Its  perfume  resembles  that  of  the  iris  or  the 
violet.  It  melts  at  from  30°  to  35°  G.,  according  to 
its  age,  but  when  freshly  prepared  its  melting-point  is 
lower.  It  is  easily  soluble  in  alcohol,  and  still  more 
so  in  sulphide  of  carbon  and  ether.  About  80,000 
tons  are  annually  manufactured.  The  oil  mixes 
readily  with  water,  which  is  frequently  used  to  adul- 
terate it;  50  per  cent. 'may  be  added  without  fear  of 
detection  by  the  most  practiced  eye.  In  order  to 
estimate  the  water  contained  in  palm  oil,  a certain 
weight  of  it  must  be  heated  on  a stove  at  110°  C. ; 
desiccation  will  then  ensue  in  a few  hours.  Unadul- 
terated commercial  palm  oil  contains  from  three  to 
eight  per  cent,  of  moisture.  A very  superior  quality 
of  oil  is  obtained  from  the  kernels  of  the  palm,  which 
are  very  large. 

Ash. — Sand  or  earth  is  frequently  mixed  with  palm 
oil  during  manufacture.  To  estimate  this,  calcine  50 


IMPURITIES. 


303 


grins,  of  oil  in  a porcelain  capsule,  and  after  the  char- 
coal thus  formed  is  burnt  off,  weigh  the  ash  obtained. 
Palm  oil  sometimes  contains  from  four  to  live  per 
cent,  of  sand. 

Imjpuriiies. — Sundry  organic  substances,  such  as 
the  remains  of  palm  leaves,  etc.,  also  occur.  In  order 
to  estimate  these,  melt  100  grins,  of  oil  in  a capsule 
upon  a water-bath,  let  it  stand  an  hour,  decant  the 
limpid  oil,  and  treat  the  precipitated  impurities  with 
sulphide  of  carbon,  so  as  to  dissolve  the  oil  which 
adheres  to  the  sides  of  the  vessel.  The  impurities 
must  be  thrown  on  a filter,  washed  with  sulphide  of 
carbon,  dried  at  100°,  and  weighed.  Some  analysis 
are  subjoined  : 


Loss  IN  Palm  Oil. 


I. 

II. 

Moisture, 

8.25 

3.12 

Ash, 

0.45 

1.20 

Organic  impurities. 

1.01 

0.80 

Total  loss. 

9.71 

5.12 

Palm  oil  produces  a beautiful  soap.  It  is  mostly 
employed  after  having  undergone  a bleaching  process, 
which  is  effected  in  the  following  manner : The  yellow 
palm  oil  is  heated  in  a wooden  tank  to  120° 
Fahr.,  chromic  acid  in  its  purity  is  then  added,  or  five 
pounds  red  or  bichromate  of  potassa  dissolved  in  hot 
water  is  put  in  the  tank  under  much  agitation,  and  ten 
pounds  chlorohydric  (muriatic)  acid  and  two  and  one- 
half  pounds  oil  of  vitriol,  all  of  which  is  the  propor- 
tion for  1,000  pounds  palm  oil  to  be  bleached  ; after  a 


304 


SOAP  MAKING. 


little  while  the  process  is  completed  and  left  to  settle, 
the  oil  appears  perfectly  decolorized,  and  produces  a 
soap  of  most  brilliant  whiteness,  and  is  employed 
with  tallow,  about  20  per  cent,  to  100  of  the  latter, 
and  is  also  a great  deal  used  in  the  rosin  soap,  for  the 
purpose  of  covering  the  flavor  and  brighten  the  color 
of  the  latter. 

Olive  Oil. — It  is  imported  from  the  southern  ports 
of  Europe,  and  is  obtained  from  the  fruit  of  the  olive 
tree.  The  virgin  oil  is  the  best  oil  obtained  from 
fresh  gathered  fruit.  Olive  oil  is  often  adulterated 
with  cheaper  and  also  animal  oils;  it  makes  the  best 
soap.  The  well  known  Windsor  and  Marseilles  soaps 
are  produced  with  it. 

Oil  of  Poppy. — The  bruised  seed  of  the  poppy 
plant  produces  a flne  oil ; it  remains  liquid  to  zero,  Fhr., 
is  a drying  oil.  It  is  used  in  France,  combined  with 
tallow,  for  the  imitation  of  Marseilles  soap. 

The  following  vegetable  butter,  such  as  the  golam^ 
a product  of  an  African  tree,  of  a reddish  white  color, 
and  containing  82  per  cent,  stearine,  and  another  butter 
from  the  African  butter  tree.  The  stillingia  butter  is 
imported  from  China  ; it  is  white  and  harder  than 
tallow.  The  tree  grows  in  the  valley  of  Chusan. 

The  mofurra  tallow  from  Madagascar,  extracted 
from  the  kernels,  which  are  of  the  size  of  a cocoa  bean, 
is  of  yellowish  color,  and  in  odor  similar  to  cocoa  oil; 
it  forms  a brown  soap  with  alkalies. 

The  Animal  Fats. 

They  contain  more  stearine  and  margarine  than  the 
vegetable  fats,  and  are  distinguished  by  their  color. 


ANIMAL  FATS. 


305 


odor  and  consistency.  There  is  much  difference  in  the 
consistency  of  the  animal  fats.  The  fat  or  oil  of  whales 
is  generally  fluid,  that  of  the  carnivorous  animals  soft 
and  rank  flavored,  and  in  the  ruminants  nearly  scent- 
less. Xor  is  the  degree  of  firmness  the  same  in  all 
parts  of  the  organism  ; the  fat  from  the  kidneys  is 
generally  harder  and  more  compact  than  that  in 
cellular  tissues  and  bowels  of  animals,  and  the  fat  of 
the  female  is  generally  softer  than  that  of  the  male. 
The  color  and  odor  of  the  fats  have  an  influence  in 
the  manufacture  of  soap. 

Beef  Tallow. — This  animal  fat  is  well  known  ; that 
rendered  by  steam  is  generally  the  whitest,  has  a 
yellowish  tint,  which  may  be  removed  by  several 
washings  in  hot  water ; it  is  firm  and  brittle;  its  melt- 
ing point  is  111°  Fahr.,  and  becomes  solid  at  102° 
Fahr.  The  tallow  from  different  countries  are  brought 
to  market  and  command  a different  price,  such  as  the 
Fussian,  South  and  hfortli  American. 

Mutton  Suet. — It  is  richer  in  stearine  than  beef 
tallow ; when  the  fat  is  stale  the  smell  is  most  disa- 
greeable and  nauseating.  It  is  generally  compact, 
firmer  and  whiter,  and  of  less  odor  than  beef  tallow.  It 
yields  a beautiful  wdiite  soap  when  saponified  with 
soda  lye,  but  may  become  too  hard  and  brittle  on 
account  of  its  richness  in  stearine,  and  in  the  saponi- 
fication about  20  per  cent,  lard  oil  is  added. 

Lard  or  Hoffs  Fat. — By  freeing  the  adipose  matter 
of  the  hog  from  the  membranous,  and  melting  it  at 
moderate  heat,  so  as  to  separate  the  fat  from  the 
cracklings,  we  obtain  a fine  lard,  which  has  agranular 
appearance  and  can  be  pressed  for  oil  without  any 
further  manipulation.  That  from  hogs  which  have 


306 


SOAP  MAKING. 


been  corn  fed  has  the  greatest  consistency ; it  has,  when 
fresh,  a mild  and  agreeable  taste.  The  consistency  of 
butter  and  its  melting  point  is  at  81°  Fahr. ; consists 
of  62  per  cent,  liquid  fat  or  olein,  and  38  per  cent, 
solid  fat.  It  yields  a fluid  called  lard  oil  when  gran- 
ulated and  pressed  at  a low  temperature.  The  pressed 
cake,  consisting  chiefly  of  stearine,  is  termed  solar 
stearine,  and  used  exclusively  in  the  manufacture  of 
candles  ; it  forms  a white,  sweet  and  pure  soap. 

Horse  Fat. — It  is  mostly  extracted  by  steam  from 
different  parts  of  dead  horses  ; it  is  from  a white  to 
brown  color,  and  every  horse  yields  about  one  hundred 
pounds.  The  soap  from  horse  fat  is  white  and  Arm, 
but  has  a very  peculiar  odor. 

Bone  Fat, — Fresh  bones  are  used  for  extracting  the 
fat,  which  is  about  5 per  cent. ; it  permeates  the  bones 
when  kept  for  some  time,  and  makes  the  extraction 
very  difflcult.  It  is  recommended  for  purifying  and 
deodorizing  bone  fat,  by  means  of  saltpetre  and  sul- 
phuric acid,  which  are  melted  together  ; will  pro- 
duce a fat  of  a light  yellow  color. 

Fish  Oil. — The  fat  of  several  species  of  the  whale 
fisli,  such  as  the  cachelot,  pot-flsh,  the  Greenland 
whale,  the  Antarctic  whale,  difierent  dolphin  species, 
the  norwall,  the  sea-pore,  and  several  species  of  ribbon 
and  mammifera  belong  to  one  class  of  whales,  and  they 
all  have  their  specific  names.  The  white-fish  oil  is  an 
oil  which  flows  out  spontaneously  from  the  fat  heaped 
up  in  a reservoir.  The  name  of  train  oil  alludes  to 
the  foiled  fish  oils^  which  are  of  inferior  quality.  Fish 
oils  are  used  as  a burning  fluid,  for  soft  soaps,  adultera- 
tion of  other  oils,  and  the  manufacture  of  chamois 
leather. 


ELAIDIC  ACID. 


307 


Sperm  Oil  and  Spermaceti. 

In  the  head,  and  special  cavities  of  the  head  of 
several  sperm  whales,  especially  of  the  pot-fish,  or 
cachelot,  and  of  some  dolphins,  there  is  a liquid  fat, 
which,  after  the  death  of  the  animal,  a large  quantity 
of  white,  firm,  tallow-like  substance  is  separated  ; the 
liquid  part  is  called  sperm  oil,  and  the  solid  sperma- 
ceti ; the  first  is.  brought  in  commerce,  bleached  or 
unbleached,  wliile  the  latter  is  more  used  for  the 
manufacture  of  candles. 

Oleic  Acid. 

This  acid  comes  in  trade  under  the  name  of  red  oil ; 
it  is  a product  from  the  manufacture  of  adamantine 
candles.  Two  kinds  of  red  oil  are  brought  into  market, 
one  formed  by  the  process  of  distillation,  which,  owing 
to  its  disagreeable  odor,  is  used  for  soft  soap  ; the  other, 
obtained  by  pressure,  yields  hard  soaps,  either  alone 
or  mixed  with  tallow  or  other  fats.  It  is  the  product 
from  stearine,  called  stearine  cake ; the  first  contains 
some  oil  vitriol,  and  has  to  be  washed  before  using  it. 

Elaidic  Acid. 

If  oleic  acid  is  treated  with  hyponitric  or  nitrous 
acid,  a pearly  white  crystaline  substance  is  obtained, 
of  the  consistency  of  tallow,  and  is  called  elaidic  acid. 
It  is  used  with  benefit  in  soap  and  candle  manu- 
facture. 


308 


SOAP  MAKING. 


The  Manufactuke  of  Soap. 

For  the  purpose  of  the  boiling  of  the  soap  materials, 
it  is  indispensable  to  produce  a preliminary  combina- 
tion of  fat  and  lye  ; and  in  order  to  form  a union  of 
the  fats  with  the  lye,  the  latter  should  be  perfectly 
pure;  and  the  same  may,  during  this  first  operation, 
be  of  the  same  strength,  or  be  commenced  with  a 
weak  lye,  then  of  middle  strength,  and  finish  with  a 
strong  one ; tlie  first  may  be  from  10  to  15°  B.,  and 
the  second  to  begin  with  one  of  7 to  10°  B. ; 15  to 
18°  B. ; and  lastly,  18  to  20°  B. 

In  the  manufacture  of  red  oil  soap,  very  strong  lyes 
are  employed,  from  25  to  30°  B.  Usually,  the  fat  is 
first  put  in  the  pan,  and  then  the  lye  is  added  ; but  it 
is  absolutely  necessary  that  the  lye  be  caustic  and  not 
carbonated,  which  will  not  decompose  any  fat,  and 
therefore  not  unite. 

By  transforming  one  hundred  pounds  of  fat  into 
soap,  fourteen  pounds  of  caustic  soda  are  necessary, 
generally  more  is  employed ; it  is  gradually  and  in 
small  quantities  added,  as  a large  quantity  of  lye 
added  at  once  will  never  act  so  energetically  upon  the 
fat  as  might  first  be  supposed.  When  one-quarter  of 
the  lye  is  added  in  the  beginning,  it  soon  forms  with 
the  fat  a milky  liquid,  which,  in  heating,  gradually  be- 
comes clearer,  producing  a transparent  soap  solution, 
with  intermingled  fat  drops  ; more  lye  is  added  under 
constant  stirring,  until  the  entire  quantity  of  the  same 
is  consumed.  This  operation  is  called  the  pasting^  for 
it  displays  a uniform  clear  mass,  where  neither  lye 
nor  fat  can  be  distinguished.  It  shows,  moreover,  that 
the  right  proportion  of  fat  and  lye  have  been  em- 


MANUFACTURE  OF  SOAP.  * 


309 


ployed.  When  the  spinning  of  the  soap  makes  its  ap- 
pearance, that  is,  when  the  paste  no  longer  drops  from 
the  stirring  rod,  but  slides  down  in  long  threads,  the 
operation  is  complete. 

The  second  operation  in  the  rnannfactnre  of  soap 
is  the  salting  process,  to  add  dry  salt,  or  the  same  in 
solution,  for  the  reason  that  soap  is  insoluble  in  brine 
or  strong  caustic  lyes,  while  weak  lyes  dissolve  it ; this 
operation  is  also  called  the  “ cutting  up  the  pan.” 
Upon  this  principle  the  mainne  soap  is  manufactured 
from  the  cocoanut  oil  soap,  which  is  so  serviceable  for 
washing  in  salt  water,  as  this  soap  possesses  the  re- 
markable property  of  being  dissolved  by  a brine  solu- 
tion. The  salting  operation  is  effected  by  gradually 
stirring  the  paste  wdth  a stirring  rod  from  below,  up- 
wards, through  the  brine  or  dry  salt.  Twelve  to  six- 
teen pounds  of  salt  are  necessary  for  one  hundred 
pounds  of  fat,  and  after  half  the  quantity  of  this  salt 
is  added,  the  soap  ought  to  be  boiled  up  for  about  ten 
minutes.  The  separation  is  perfect  when  the  water  is 
observed  to  run  off  from  the  curdy  mass,  and  when  on 
placing  some  of  the  soap  in  the  palm  of  the  hand  and 
rubbing  it  with  the  thumb,  it  hardens  into  firm  scales  ; 
or  when  the  surface  splits  up  into  several  fields,  sepa- 
ted  from  each  other  by  deep  furrows;  the  soap  which 
was  covered  with  froth  and  bubbles  suddenly  sinks, 
and  the  froth  breaks  up  into  roundish  massive  grains, 
distinctly  separated  from  each  other  and  from  the 
saline  solution.  The  mass  shoiTld  be  left  quiet  for 
several  hours,  and  the  under  lye  (nigger)  drawn  off  by 
the  faucet. 

The  third  operation  is  the  clear  boiling  of  the  soap, 
so  as  to  obtain  hardness,  consistency  and  complete 

14^ 


310 


SOAP  MAKING. 


neutrality  of  the  soap.  The  paste  is  boiled  gently 
with  tolerably  strong  lyes,  in  certain  proportions,  and 
boiled  for  eight  hours;  the  lye  is  then  drawn  off,  and 
a second  boiling  with  lye  is  undertaken  and  drawn  off 
again  ; a quick  union  of  the  alkali  with  the  fat  is 
thereby  obtained  ; the  process  is  terminated  when  large, 
regular  and  dry  scales  appear  on  the  surface,  which 
are  easily  pulverized  by  rubbing  them  in  the  palm  of 
the  bands ; the  soap  should  then  be  covered,  left  for 
some  time,  and  eventually  removed  iu  the  ladles. 

Saponification  by  Pbessube  and  Agitation. 

The  latest  improvements  in  saponification  consist 
either  in  pressure  or  agitation.  The  first  is  Rogers’ 
patent  process,  where  the  agitation  is  performed  at  a low 
temperature,  and  not  alone,  as  much  time  is  saved  to 
produce  a thorough  saponification,  but  also  the  bleach- 
ing of  the  soap  is  affected,  so  that  inferior  stock  may 
be  employed  in  the  manufacture  of  soap.  According 
to  him,  is  the  following : Into  an  iron  tank  the 

mixture  is  put,  and  then  forced  by  means  of  a force- 
pump,  and  a pressure  of  about  400  pounds  to  the 
square  inch  ; the  mass  is  forced  into  a cylinder  by 
steam  ; here  it  remains  until  complete  saponification 
is  effected ; it  is  then  drawn  off  in  cooling  frames  and 
treated  in  the  usual  manner.  This  process  has  many 
advantages  ; the  product  is  much  firmer  and  more 
translucent  soap,  and  the  caustic  soda  may  be  substi- 
tuted for  carbonate  of  soda,  even  in  smaller  propor- 
tions. 

Saponification  by  agitation  is  effected  by  an  appa- 
ratus, consisting  in  a cylinder,  six  feet  in  diameter 


PROCESS  OF  SAPONIFICATION. 


311 


and  twelve  feet  long,  and  capable  of  working  two  and 
one-half  tons  of  tallow  with  twenty  gallons  of  lye,  of 
1.125  specific  gravity,  forcing  100  pounds  tallow 
through  the  cylinder  lengthwise ; a shaft  extends 
with  radiated  arms,  to  which  an  oscillating  or  rotary 
motion  is  communicated ; agitation  is  kept  up  for  three 
hours,  the  mass  is  then  left  undisturbed  for  a short 
time,  and  then  removed  into  an  open  boiler,  and  com- 
pleted in  the  ordinary  way.  The  following  processes 
were  reported  by  the  commissioner  to  the  Paris  Expo- 
sition in  1867 : 

The  De  Milly  and  Motard  Process  of  Saponi- 
fication. 

After  the  lime  soap  is  formed,  it  is  decomposed  by 
sulphuric  acid,  and  the  resulting  fatty  acids  are  cooled 
in  shallow  tin  or  copper  pans,  in  rooms  of  about  60° 
Fahr.,  so  as  to  allow  of  the  proper  crystalization  of 
the  solid  acids.  The  next  step  is  to  press  these  acid 
cakes,  which  is  first  done  in  a cold  press,  then  in  a 
hot  press,  first  suggested  by  Cambaceres,  but  success- 
fully carried  out  by  the  horizontal  presses  invented  by 
De  Milly  and  Motard,  and  now  universally  employed 
in  candle  factories. 

The  difiiculties,  however,  of  these  indefatigable 
manufacturers,  were  far  from  being  overcome  ; the 
pans  colored  the  fats  with  iron,  the  last  trace  of  lime 
was  not  removed,  and  the  candle  made  had  a crystal- 
ine  ^itructure.  By  the  alternate  application  of  steam 
and  dilute  sulphuric  acid,  and  white  of  egg  and  oxalic 
acid,  they  overcame  the  first  difficulty.  \^arious 
means  were  tried  to  prevent  the  crystaline  structure. 


312 


SOAP  MAKING. 


commencing  with  the  objectionable  use  of  arsenious 
acid,  then  the  more  expensive  one  of  wax,  w'hich  also 
had  a tendency  to  color  the  candle  They  at  last 
triumphed  over  this  difficulty,  by  cooling  the  acids  to 
a temperature  near  their  point  of  solidification  before 
introducing  them  into  the  m-olds,  that  were  first  raised 
to  the  temperature  of  the  cooling  fats.  During  the 
cooling  of  the  mass  it  is  constantly  agitated,  and  a 
pasty  liquid  is  produced,  which  congeals  in  the  molds 
without  crystalization.  Three  years  had  now  elapsed 
since  the  first  establishment  of  their  factory,  the  com- 
mercial results  of  which  had  been  a failure.  M.  De 
Milly  now  came  into  the  possession  of  the  factory 
alone,  his  faith  in  its  success  remaining  firm,  and  two 
years  later,  in  June,  1836,  he  gave  the  perfecting 
touch  to  the  successful  manufacture  of  star  candles. 
The  wick  has  always  been  a source  of  great  annoyance 
in  the  burning  of  the  candles,  for  the  small  amount 
of  mineral  matter  in  the  candle  stuff  would  accumu- 
late in  the  wick,  and  interfere  with  the  free  flowing  of 
the  melted  fat.  After  numerous  trials  by  saturating 
the  wick  with  different  substances,  the  required  result 
was  successfully  accomplished,  by  impregnating  the 
wick  with  a certain  quantity  of  boracic  acid,  dissolved 
in  water,  containing  one-thousandth  of  its  weight  of 
sulphuric  acid.  The  boracic  acid,  as  the  combustion 
of  the  candle  progressed,  united  with  the  lime  and 
the  ashes  of  the  wick,  forming  a very  fusible  salt, 
which  accumulated  on  the  end  of  the  wick,  forming  a 
small  drop. 


SULPHURIC  ACID  SAPONIFICATION. 


313 


Sulphuric  Acid  Saponification. 

This  method  was  discovered  by  Chevreiil  in  his 
original  researches  on  fatty  bodies;  and  in  the  patent 
taken  out  by  him  in  conjunction  with  Gay  Liissac,  in 
1825,  this  method  is  specified,  but  certain  portions  of 
the  fats  were  so  altered,  as  to  discolor  the  product  to 
such  an  extent  as  to  render  it  of  no  use  in  practice. 
The  acids,  however,  thus  formed,  could  be  distilled 
more  or  less  perfectly,  as  lirst  shown  by  Chevreul,  and 
subsequently  practically  executed  by  Dubrunfaut. 
But  the  first  idea  of  combining  the  two  operations, 
viz.,  sulphuric  acid  saponification  followed  by  distilla- 
tion, is  due  to  Coley  Jones  and  Wilson,  of  England, 
subsequently  perfected  by  Gwinne  and  Jones. 

The  process,  as  it  is  now  carried  out,  may  be 
summed  up  as  follows  : The  fat  is  placed  in  large 

vessels,  that  may  be  of  wood  or  masonry,  lined  with 
lead,  and  from  six  to  fifteen  per  cent,  of  concentrated 
sulphuric  acid  is  added ; the  mixture  is  then  heated 
by  a steam  coil,  to  near  the  temperature  of  boiling- 
water,  and  maintained  at  that  temperature  eighteen 
or  twenty  hours.  Some,  however,  operate  at  a higher 
temperature,  and  consume  less  time  in  the  reaction, 
with  as  much  as  thirty  per  cent,  of  sulphuric  acid  and 
agitation,  decomposing  batches  of  two  hundred  pounds 
in  four  minutes.  The  fat  is  decomposed  with  an 
alteration  of  part  of  the  glycerine  and  part  of  the  fat, 
sulphurous  acid  and  carbonic  acid  being  evolved.  The 
black  mass  resulting  from  the  action  of  the  sulphuric 
acid  is  now  thoroughly  washed  by  boiling  water,  until 
all  the  fatty  acids  are  freed  completely  from  sulphuric 
acid.  The  fatty  acids  are  now  introduced  into  larg( 


314 


BOAP  MAKING. 


cast-iron  stills,  capable  of  holding  over  one  ton  of 
these  acids.  The  stills  are  heated  from  below,  so  as 
to  bring  the  contents  to  the  temperature  of  260°  C., 
when  a jet  of  superheated  steam  of  350°  to  380°  C. 
is  made  to  traverse  the  charge,  and  in  about  twelve 
hours  the  matter  is  distilled  over,  leaving  behind  a 
pitchy  substance,  which  may  be  used  in  the  manufac- 
ture of  gas,  or  for  coating  roofs,  and  other  purposes  in 
the  arts.  The  fatty  acids,  when  distilled,  may  be 
cooled  in  pans,  and  submitted  to  the  cold  and  hot 
pressure ; for  some  purposes  it  is  submitted  only  to 
the  cold  pressure,  and  in  England  is  much  used  with- 
out any  pressure  at  all,  when  palm  oil  has  been  the 
fat  acted  upon. 

Saponification  by  Sulphuric  Acid  without 
Distillation. 

Fats  saponified  by  sulphuric  acid  by  the  ordinary 
method,  contain  more  or  less  tarry  matter,  arising  from 
the  decomposition  of  the  fats,  causing  more  or  less 
loss  in  the  raw  material. 

M.  De  Milly  undertook  a series  of  experiments,  by 
which  he  finally  showed  that  fats  could  be  saponified 
by  sulphuric  acid  without  the  formation  of  tarry 
matter.  This  point  being  established,  he  further 
showed  that  the  fatty  acids  obtained  without  the 
formation  of  tarry  matter,  were  identical  with  the 
fatty  acids  formed  by  the  lime  saponification.  These 
he  submitted  to  cold  and  hot  pressure  under  special 
conditions,  and  obtained  cakes  of  candle  stuff  most 
beautifully  white.  As  to  the  oleic  acid,  it  is  of  a dark 
color,  but  in  no  way  decomposed  ; it  makes  a fine 
brown  soap,  or  it  can  be  distilled  and  made  white. 


MANUFACTURE  OF  FAMILY  SOAPS. 


815 


M.  Balard,  in  a report  on  this  process,  expresses 
himself  in  the  following  terms  : 

“ In  the  establishment  of  M.  De  Millj,  the  fat  is 
melted  and  heated  to  120®  0.  ; it  is  then  allowed  to 
flow  from  its  reservoir  and  mix  with  a stream  of  strong 
sulphuric  acid,  in  the  proportion  of  six  per  cent,  of 
the  latter.  The  mixture  is  rendered  perfect  bj  means 
of  agitation.  The  action  takes  place  immediately, 
and  is  arrested  in  two  or  three  minutes,  by  allowing 
the  mixture  to  flow  into  boiling  water,  when  the 
sulphuric  acid  and  unaltered  glycerine  enters  into 
solution,  and  the  fatty  acids  float  on  the  surface, 
being  of  a dark  color.  But,  contrary  to  what  takes 
place  in  the  ordinary  method  of  saponiflcation  by 
sulphuric  acid,  the  coloring  matter  is  completely 
soluble  in  the  liquid  fat  acid,  so  that  by  cold  and  hot 
compression,  the  solid  fat  acids  are  obtained  perfectly 
white,  ready  to  be  molded  into  candles.  The  entire 
operation  can  be  accomplished  in  one  hour.’^ 

The  Manufacture  of  Family  Soaps, 

There  are  generally  four  different  kinds  of  soap 
brought  into  market,  which  consist  in — 1.  Hard  ; 2. 
Soft ; 3.  Toilet  or  perfumed  ; and  4.  Silicated  soaps. 

The  hard  soaps  are  invariably  made  from  soda ; 
they  are  divided  in  boiled  soaps  and  those  made  in 
the  cold  way.  Another  division  is  made  among  hard 
soaps,  such  as  grained^  or  those  where  the  separation 
of  the  underlye  (nigger)  has  been  made,  as  has  been 
already  noticed  under  the  head  of  cutting  up  the  pan, 
and  in  filled  soaps,  or  such  where  the  whole  contents 
of  the  boiling  pan  are  kept  and  crutched  together, 


816 


^OAP  MAKING. 


and  sold  as  soap.  The  more  solid  constituents  a fat 
contains,  the  harder  is  the  soap,  and  the  more  oleine, 
the  softer.  In  mixing  the  fats  in  different  proportions, 
soaps  of  every  consistency  are  obtained.  Weak  and 
middling  strong  lyes  will  produce  a light  soap,  while 
lyes  of  25°  to  o0°  B.  will  produce  a soap  heavier  than 
water.  Glauber  salt,  not  over  one  per  cent.,  is  some- 
times added  in  order  to  prevent  too  great  solubility  uf 
the  soap  in  washing  ; it  is  called  then 

ElectriG  Soap. — Bosin,  in  the  proportion  of  one- 
third  or  one-fourth  of  the  fat  employed,  is  frequently 
used,  and  the  soap  is  called  Rogers’  soap.  Twelve 
and  one-half  pounds  of  solid  caustic  soda  are  usually 
consumed  for  100  pounds  of  fat,  for  its  conversion 
into  soap.  A new  soap,  composed  of  the  rosin  soap, 
to  which  is  incorporated  a mixture  of  spirits  of  tur- 
pentine, ammonia  and  pearl  ashes,  and  by  other  man- 
ufacturers a quantity  of  flour  and  benzine  are  added 
to  the  above  mixture,  and  all  crutched  in  the  rosin 
soap. 

Tallow  Soaps. 

The  most  ancient,  and  at  the  same  time  the  most 
important,  is  the  tallow  soap;  it  is  cheap,  and  called 
for  by  everybody,  both  in  the  household  and  the  man- 
ufactory. The  following  is  the  mode  pursued  by  the 
most  experienced  soap  makers  : To  1,000  pounds  fat, 

which  is  melted  at  a slow  heat,  from  70  to  80  gallons 
lye,  standing  10  to  12°  B.,  are  added  and  kept  stirring 
under  a gentle  fire  for  several  hours.  Should  a part 
of  the  fat  separate  from  the  mass,  which  is  often  the 
case,  an  oily  liquid  will  be  observed  floating  on  tlie 
top  ; it  requires  then  the  addition  of  35  to  40  gallons 


TALLOW  SOAPS. 


317 


more  Ije,  of  15  to  18°  B.,  whereby  the  whole  contents 
will  form  quickly  a homogeneous  mass  of  a grayish 
white  color ; a gentle  boiling  must  be  kept  up  for 
several  hours,  and  adding  every  hour  six  to  seven  gal- 
lons of  lye  of  20°  B.,  when  the  paste  assumes  the 
proper  consistency  ; this  operation  requires  ten  to 
twelve  hours.  And  then  the  second  operation  has  also 
been  described  under  the  salting  process,  w^here  the 
ingredients  have  to  be  well  stirred  while  adding  the 
salt,  and  after  separation  has  taken  place,  several 
hours  are  necessary  for  settling ; and  then  to  draw  off 
the  colored  underlye,  90  gallons  of  lye  of  25°  should 
then  be  added,  and  the  heat  increased,  so  as  to  preserve 
the  soap  from  bubbling.  The  wdiole  mass  is  then 
boiled  from  ten  to  twelve  hours,  adding  every  hour 
five  gallons  lye  of  25°  B.  ; but  after  boiling  four  to  five 
hours,  the  operation  is  perfected,  and  the  fire  with- 
drawn, left  quiet  for  an  hour,  and  the  underlye  is 
drawn  off ; the  soap  will  then  separate  from  the  lye 
and  rise  to  the  top ; after  five  to  six  hours,  while  yet 
liquid,  it  is  put  in  pails  or  ladles,  into  the  frames, 
taking  much  care  that  no  lye  is  mixed  with  it.  In 
the  frames,  which  are  either  of  wood  or  iron,  it  must 
be  well  stirred  and  crutched  for  some  time.  In  order 
to  cover  the  not  agreeable  smell  of  the  tallow,  two 
ounces  of  oil  of  mirbane  should  be  added  to  every  100 
pounds  of  soap  ; after  seven  to  eight  days  it  may  be 
cut.  100  pounds  of  tallow^  will  yield  from  165  to  170 
pounds  of  soa]>. 

Tallow  Eosix  Soaps. 

It  is  well  ascertained  that  the  addition  of  rosin,  to 
a certain  amount,  will  make  the  soap  more  detergent. 


318 


SOAP  MAKING. 


more  soluble  and  cheaper ; it  does  form  a soap  with 
the  tallow  ; 15  per  cent,  rosin,  and  85  per  cent,  tallow, 
make  a good  proportion  ; any  excess  will  depreciate 
the  soap  in  firmness  and  quality ; the  soap  will  become 
clammy  if  33  per  cent,  are  used  ; it  will  be  too  soft ; 
but  twelve  gallons  of  lye  of  30°  B.  may  be  used 
for  every  100  pounds  of  rosin ; it  may  be  melted 
with  the  fat  in  the  commencement  of  the  boiling  for 
soap,  although  it  is  more  expedient  to  make  first  the 
tallow  soap,  and  then  mix  the  rosin  soap,  compounded 
in  another  kettle,  to  the  first.  Both  soaps  have  then 
to  be  well  stirred  and  beaten  thoroughly  for  half  an 
hour,  and  then  passed  through  a sieve,  before  they  are 
filled  into  the  frames,  where  they  are  also  well  stirred 
and  crutched.  By  adding  to  the  saponified  tallow 
some  palm  oil,  the  appearance  of  the  soap  will  be 
thereby  much  improved. 

A practical  soap  maker  stated  to  the  writer  a short 
time  ago,  that  he  uses  ten  pounds  of  tallow,  nine 
pounds  of  rosin,  and  five  pounds  of  tilling  of  sal  soda 
and  starch,  which  he  adds  after  the  saponification  has 
taken  place. 


CocoANUT  Oil  Soap. 

This  oil,  as  already  mentioned,  acts  dififerently  from 
any  other  fats,  in  combination  with  which  weak  lyes 
produce  a milky  mixture.  A lye  of  27°,  when  cold, 
will  saponify  100  pounds  cocoanut  oil,  and  produce 
200  pounds  soap.  The  process  is  very  simple  : the  oil 
and  lye  are  put  together,  and  the  heat  is  applied  ; 
after  stirring  for  one  or  two  hours,  the  paste  is  seen 
thickening  gradually,  and  the  heat  is  moderated  while 


CASTILE  OR  SPANISH  SOAP. 


319 


tlie  stirring  is  continued.  After  a while  the  paste  be- 
comes transformed  into  a white  semi-solid  mass,  which 
forms  the  soap,  and  this  has  to  be  filled  immediately 
into  the  frames,  as  solidification  quickly  ensues.  Equal 
parts  of  tallow  and  cocoanut  oil,  or  only  cocoanut  and 
palm  oil,  (bleached,)  yield  a very  fine  soap  ; also,  90  to 
95  per  cent,  cocoanut  oil  with  5 to  10  per  cent,  natural 
palm  oil,  yield  a fine  soap  ; the  saponification  takes 
place  of  fats  and  cocoanut  oil,  if  not  in  too  large  a 
proportion.  It  is  to  be  remarked,  that  the  mixture 
of  cocoanut  oil  and  other  fats  and  lye  need  not  be 
separated  with  brine. 

Castile  or  Spanish  Soap. 

This  is  also  a hard  soap,  a pure  olive  oil  soda  soap, 
and  is  imported  here  under  two  principal  varieties, 
the  white  and  the  marbled.  The  white  Castile  soap 
is  of  a pale  grayish  white  color,  does  not  give  an  oily 
stain  on  paper,  devoid  of  rancid  odor  or  strong  alka- 
line qualities,  entirely  soluble  in  water  and  alcohol. 
It  becomes  dry  by  exposure  to  the  air  without  dis- 
playing any  efflorescence ; it  contains  21  per  cent, 
water. 

The  marbled  Castile  soap  is  harder,  more  alkaline 
and  more  constant  in  its  composition,  and  contains 
but  14  per  cent,  water  ; it  is,  therefore,  stronger  than 
the  first,  and  more  economical.  The  process  of  mar- 
bling, which  is  explained  on  page  324,  is  by  pro- 
ducing veins  of  ferruginous  matter,  makes  the  mar- 
bled soap  somewhat  impurer.  This  soap  is  mostly 
used  in  medicine,  for  the  manufacture  of  opodeldoc, 
suppositories  and  in  pills,  and  in  great  demand  for 


320 


SOAP  MAKING. 


family  use ; particularly  the  genuine  soap,  which  is 
brought  from  Marseilles  in  small  boxes  and  bars, 
weighing  from  three  to  four  pounds  each.  It  is  much 
imitated  in  Paris  an(f  London,  and  instead  of  olive 
oil,  tallow  is  mixed  with  it,  which  can  be  detected  by 
analysis. 

Soft  Soaps. 

The  difference  between  potash  and  soda  soaps  con- 
sists in  the  difference  of  consistency  ; the  one  is  hard, 
and  the  latter  soft,  while  the  first  is  clearer  and  purer, 
the  other  is  darker,  smeary  and  much  cheaper.  Fish 
oils  and  red  oils  are  mostly  employed  for  soft  soaps, 
therefore  much  cheaper. 

Saponification  is  commenced  with  a lye  of  9 to  11° 
B.,  and  the  contents  of  the  kettle  kept  boiling  until 
the  paste  becomes  of  sufficient  consistency  to  draw 
threads,  as  it  were,  out  of  a streak}^  substance.  It  then 
undergoes  the  process  of  clear  boiling,  for  which  pur- 
pose lye  of  25°  B.  should  be  used.  It  must  be  stirred 
constantly;  but  when  the  paste  does  not  sink  any  more, 
(first  it  ascends,)  boils  quietly  and  shows  the  formation 
of  scales,  it  may  be  considered  complete.  The  barrels 
should  be  immediately  filled,  in  which  it  is  to  be 
offered  to  the  trade.  Hempseed  oil  is  used  in  Prussia 
for  soft  soap,  which  is  quite  green ; but  whale  oil  is 
principally  employed.  Many  other  oils,  such  as  lin- 
seed oil,  poppy  oil,  rapeseed,  colza  and  cotton  seed,  are 
all  used  for  a smear  soap  ; and  in  order  to  give  the  de- 
sired color  of  soft  soap,  various  colors  are  added  to  it, 
such  as  indigo  solution,  with  lime,  &c. 


SILICA  SOAPS. 


321 


Palm  Oil  Soaps. 

Palm  oil  is  rarely  used  exclusively  as  a soap  stock  ; 
it  is  generally  employed  with  rosin  for  obtaining  a 
yellow  soap.  White  soap  from  the  bleached  palm  oil, 
combined  with  the  cocoanut  oil,  is  in  great  demand, 
say  ten  per  cent,  of  the  latter  to  ninety  per  cent,  of 
palm  oil,  as  with  filled  soaps.  Tallow  and  palm  oil, 
with  a small  quantity  of  rosin  and  cocoanut  oil,  pro- 
duce a fine  and  hard  soap. 

The  following  receipts  are  known  to  the  principal 
soap  manufacturers  : 


Palm  oil. 

300  lbs. 

Palm  oil,  450  lbs. 

Tallow, 

200 

Cocoanut  oil,  50 

Rosin, 

20 

Hog’s  lard,  550  ‘‘ 

Tallow, 

500 

Palm  oil,  150 

Palm  oil. 

300 

Cocoanut  oil,  50 

Rosin, 

200  “ 

Rosin,  50  “ 

Palm  oil  may 

be  made  into 

soap  in  the  same  manner 

as  tallow,  and  if  rosin  is  to  be  incorporated,  it  is  best 
to  produce  first  the  combination  of  the  rosin  with  the 
lye,  and  then  mix  the  same  with  the  finished  palm  oil 
soap.  Palm  soap  becomes  bleached  when  exposed  to 
the  light. 


The  Silica  Soaps. 

All  soaps,  whether  hard  or  soft,  and  whetlier  for 
domestic  use  or  family  soap,  or  for  manufacturing 
purposes,  bear  safely  an  admixture  of  silicate  of  soda, 


322 


SOAP  MAKING. 


to  the  extent  of  20  to  25  per  cent.  (35°  B.)  to  the 
ready  prepared  cold  soap ; but  it  requires  that  the 
silicate  be  perfectly  neutral,  for  if  there  is  the  least 
trace  of  fatty  acid,  silica  will  be  precipitated,  and  the 
alkali  will  effloresce  from  the  soap  after  a short  time. 
Tlie  dissolved  silica,  either  the  silicate  of  soda  or 
potassa,  of  about  1.4  specific  gravity,  is  gener- 
ally added  while  the  soda  soap  is  still  hot,  but  is 
previously  transferred  from  the  cauldron  into  a tub  or 
pan,  called  the  mixing  vessel,  capable  of  containing 
about  1,400  weight  of  soap,  and  the  silicate  is  to  be 
added  in  such  proportions  as  to  yield  the  particular 
quality  of  soap  desired  to  be  produced  ; the  mixture 
is  then  well  agitated  by  means  of  crutches  or  paddles. 
The  soap  and  the  viscous  solution  should  each  be  at 
such  a degree  of  heat,  that  the  mixture,  when  formed, 
may  be  at  a temperature  of  160°,  and  the  agitation  is 
to  be  continued  until  the  temperature  is  reduced  10°, 
or  150°.  The  mixture  is  then  transferred  to  the  cool- 
ing frames,  and  agitated  therein  by  means  of  crutches, 
until  it  becomes  of  such  consistence  as  to  render  its 
continuance  no  longer  practicable.  If  a more  rapid 
agitation  could  be  applied,  the  soap  produced  is  a 
more  perfect  mixture,  and  more  uniform.  The  solu- 
tion of  silicate  of  soda  at  35°  B.  is  well  for  an  addi- 
tion to  any  soap.  The  curd  or  white  soap,  the  yellow 
or  rosin  soap,  the  palm  and  olive  soaps,  may  all  be 
treated  with  the  addition  of  20  to  25  per  cent,  of 
soluble  glass,  standing  from  25°  to  35°  B.,  and  the^ 
manipulator  will  succeed  in  producing  a good  deter- 
gent soap,  which  will  not  crust  after  a short  time  if 
the  following  rule  is  observed  : 

Do  not  add  the  soluble  glass  until  after  the  saponi- 


SILICA  SOAP. 


323 


fication  is  complete,  and  before  the  soap  is  cold.  Use 
the  silicate  of  soda  hot,  and  as  neutral  as  possible,  and 
crutch  it  with  the  ready  made  soap  in  small  portions, 
and  do  not  use  more  than  20  to  25  per  cent,  of  the 
silicate  to  the  soap,  and  continue  the  operation  of 
crutching  for  several  hours.  In  order  to  be  able  to 
use  the  silicate  of  soda  in  a neutral  state,  for  the  com- 
mon soluble  glass  is  more  or  less  alkaline,  it  is  best  to 
add  two  pounds  of  hydrochloric  acid  to  each  twenty 
gallons  of  the  soluble  glass  solution,  standing  30°  to 
35°  B.,  and  while  hot  keep  the  acid  agitating  for  an 
hour  or  so,  when  the  same  will  become  neutral  and 
suitable  to  be  mixed  with  the  soap  in  the  mixing 
vessel. 

The  common  silica  soap  in  trade  consists  of 

90  pounds  salt, 

15  “ cocoanut  oil, 

15  “ caustic  lye, 

50  “ silicate  of  soda. 

The  soluble  glass  may  as  well  be  used  in  soft  soaps 
in  the  same  manner  as  described  for  hard  soaps.  The 
mixed  silicated  soaps  may  be  obtained  of  any  requisite 
degree  of  hardness,  by  the  greater  or  less  concentra- 
tion of  the  solution  of  soluble  glass.  The  compound 
soaps  produced  by  this  process  are  possessed  of  valu- 
able detergent  properties,  independently  of  the  real 
soap  contained  in  them.  Many  varieties  of  soap  are 
known  in  the  trade  under  the  name  of  silicated  soaps. 
Silica,  silex,  sand  and  pumice  soaps,  even  when  the 
soap  is  mixed  or  adulterated  with  white  china  clay, 
talc,  soapstone,  and  other  materials  ; those  soaps  are 
oflered  under  the  name  of  silica. 


324: 


SOAP  MAKING. 


In  the  preparation  of  sand  soaps,  the  finely  sifted 
sand  or  fiint  is  added  to  ordinary  white  soap,  and 
thoroughly  incorporated  with  it,  while  in  the  pasty 
condition,  from  eight  to  ten  per  cent.,  and  as  soon  as 
the  mass  has  cooled,  it  is  taken  from  the  frame  and  cut 
into  tablets  or  molded  into  balls. 

Mottled  or  Marble  Soap. 

In  the  manufacture  of  this  variety  of  soap,  the 
same  kinds  of  materials  are  used  as  for  white  soap, 
and  its  difierent  appearance  arises  from  the  different 
mode  of  treatment  of  the  soap,  after  the  completion 
of  saponification.  It  has  already  been  observed,  that 
even  after  the  complete  formation  of  the  soap,  that  is, 
when  the  whole  of  the  oil  or  fat  used  is  decomposed, 
and  the  oily  acids  have  entered  into  combination  with 
alkali,  the  soap  still  requires  further  treatment  before 
it  is  brought  to  market;  the  immovable  globules 
have  to  be  brought  into  a homogeneous  mass,  which 
is  effected  by  the  process  termed  fitting,  which  consists 
in  the  fusion  of  the  contents  of  the  boiling  cauldron 
in  a weak  lye  or  in  water,  and  afterwards  boiling  the 
whole  for  a longer  or  shorter  period,  so  as  to  break  the 
froth  and  favor  evaporation.  During  this  process  in 
making  white  or  curd  soap,  the  more  or  less  colored 
impurities  of  the  materials,  termed  nigger,  fall  to  the 
bottom ; but  in  making  mottled  soap,  the  mixture  is 
left  in  a thick  or  viscid  state,  so  that  the  impurities 
cannot  subside,  and  is  transposed  to  the  frames  in  this 
condition. 

To  produce  a good  marbled  soap,  it  is  necessary 
that  the  latter  operation  be  very  carefully  conducted. 


TOILET  SOAPS. 


325 


for  if  too  great  a quantity  of  liquid  be  added,  or  if  the 
mixture  of  soap  and  water  or  weak  lye  cools  too  slow- 
ly, all  the  coloring  matter  falls  to  the  bottom,  leaving 
the  upper  stratum  of  soap  perfectly  white,  while,  on 
the  other  hand,  if  it  becomes  too  quickly  cold,  the  soap 
remains  in  the  granular  condition.  The  lower  veins 
in  mottled  soap  appear  to  be  due  to  the  presence  of 
exceedingly  minute  traces  of  sulphide  of  iron,  derived 
from  the  last  service  of  lye,  in  which  it  exists  in  solu- 
tion as  a double  sulphide  of  sodium  and  iron.  At 
Marseilles  and  other  places  where  olive  oil  is  used  in 
making  soap,  a quantity  of  sulphate  of  iron  is  added, 
whereby  the  mottling  is  produced ; about  eighteen 
ounces  of  copperas  to  450  pounds  of  oil,  wdiich  is 
added,  first  mixed  with  weak  lye,  are  poured  in 
during  the  coction  of  the  soap,  and  before  it  has  ac- 
quired too  much  consistence.  When  the  soap  is  ladled 
out  of  the  boiler,  it  is  of  a uniform  slate  tint,  but  as  it 
becomes  cool,  the  metallic  portion  separates  into 
nodules,  and  by  the  trickling  of  the  excess  of  lye 
through  the  mass,  they  assume  those  forms  to  which 
the  term  mottled  is  applied.  According  to  the  tint 
of  the  sulphate  of  iron,  a lighter  or  darker  hue  appears 
on  the  surface  of  the  soap. 

Toilet  Soaps. 

The  great  variety  of  soaps  thus  designated  are  usu- 
ally prepared  by  remelting  and  clarifying  white  or 
curd  soap,  and  adding  various  perfumes,  colors,  etc., 
all  of  which  is  more  the  province  of  the  perfumer  than 
of  the  soap  maker.  The  most  convenient  method  of 
preparing  soaps  for  the  toilet  is  by  the  cold  process. 
The  fullowing  method  is  pursued  : 

15 


326 


SOAP  MAKING. 


First,  the  fat  is  melted  in  a well  cleaned  iron  or 
copper  kettle  at  a low  temperature  ; it  is  filtered  then 
through  fine  linen  or  muslin  into  another  kettle, 
when  it  is  boiled  with  one  third  of  water  for  ten 
minutes,  and  then  strained  ofif  Some  add  for  100 
pounds  of  fat,  six  ounces  salt  and  three  ounces 
fine  pulverized  alum ; they  let  it  remain  quiet  for 
some  hours,  until  it  becomes  what  is  called  figging. 
To  the  fat,  which  must  not  be  warmer  than  104® 
Fab.,  the  Ije  is  gradually  added.  In  the  soaps 
made  after  the  cold  way^  a very  strong  lye  is  used, 
say  36°  B.,  and  for  a certain  quantity  of  fat  just  half 
is  employed,  say  for  eighty  pounds  fat,  forty  pounds 
of  Ijm.  The  lye  must  be  entirely  clear  and  colorless, 
but  it  is  not  necessary  that  it  be  heated  previously, 
when  it  has  been  kept  in  a warm  room.  For  stirring 
it,  a broad  paddle  of  box-wood  must  be  used,  having 
sharp  edges  at  the  lower  end,  and  rounded  at  its  upper 
end,  so  that  it  may  be  easily  handled.  The  necessary 
coloring  matter  and  perfumery  should  be  added  as 
soon  as  a ring  drawn  with  the  spatula  can  be  recog- 
nised. The  paste  is  now  run  into  frames  previously 
lined  with  linen  ; each  frame  should  be  entirely  filled 
with  the  mass,  and  w^ell  closed  with  the  linen  and 
wooden  cover,  and  left  then  for  twelve  hours,  by 
which  time  saponification  will  have  been  efiected  ; 
the  mass,  which  was  nearly  cold  when  run  into  the 
frames,  has  undergone  a spontaneous  reaction,  raising 
the  temperature  over  175°  Fah.  The  different  con- 
stituent principles  are  now  combined  ; the  soap  pro- 
duced is  of  a quality  resembling  that  of  boiled  soaps. 
After  twelve  hours  the  soap  is  taken  out,  and  cut  and 
dried ; and  for  making  it  a little  softer  one-tenth  of 


TOILET  SOAPS. 


327 


potash  lye  is  added  to  the  soda  lye,  for  the  purpose  of 
increasing  the  solubility,  and  consequently  the  quality 
of  the  soap;  for  when  no  potassa  is  added,  these  soaps 
are  generally  hard  ; 100  pounds  of  fat  will  yield  about 
150  pounds  of  soap. 

KURTEN’S  TABLE, 


Showing  the  composition  and  yield  of  Soap  Toy  the  Cold  Process,  from 
Concentrated  Lye,  and  mixtures  of  Cocoa  Oil  with  Palm  Oil,  Lard 
and  Tallow. 


Emus  OF  Soap. 

Tallow.  1 

Cocoanut 

Oil. 

Palm  Oil. 

Lard.  | 

ao 

0> 

Si 

be 

0^ 

P 

1 Salt  Water. 

Degrees. 

1 Potash. 

1 Degrees. 

Product. 

Cocoanut  Oil,  No.  1,.  

Paris  Toilette,  (round,) 

((  (( 

Windsor,  (square,) 

Shaving',  No.  1, 

20 

66 

66 

33 

33 

60 

30 

40 

( 

100 
30 
25 
34 
34 
or 
34 
34 
40 
or 
1 40 
1 60 
or 

I 60 
IlOO 
or 
1 90 
or 
90 

*8 

75 

56 

31 

50-52 

77 

36 

36 

36 

30 

5 

13 

36 

30 

153 

87 

150 

185 

Shaving,  No.  2, 

Washing,  No.  1, 

33 

33 

120 

27 

i 

214 

120 

27 

12 

12 

226 

Washing,  No.  2, 

30 

125 

27 

25 

12 

244 

Ordinary  Cocoanut  Oil,  ... 

40 

135 

27 

50 

15 

278 

i 

101 

••1 

10 

’225’ 

21 

75 

12 

400 

The  marbling  of  these  soaps  is  produced  by  rubbing 
up  the  coloring  material,  snch  as  vermilion,  smalts,  or 
ultramarine,  with  a little  olive  oil  or  soap,  a small  por- 
tion of  which  being  taken  on  a pallet  knife,  is  pushed 
through  the  melted  mass.  Tlius  the  pink  color  of  rose 
soap  is  produced  by  vennilion  ; blue  by  means  of 
ultramarine,  and  brown  by  the  addition  of  the  various 


328 


SOAP  MAKING. 


kinds  of  ochres  and  umbers.  Generally  speaking,  the 
colors  are  varied  much,  particularly  since  the  aniline 
colors  are  so  much  used.  The  violet  is  obtained  from 
fuchsine  dissolved  in  glycerine;  green  color,  the  real 
chrome  green  is  used ; chrome  red  is  also  employed 
for  a red  coloring,  and  caromel  or  sugar  coloring  for 
producing  a good  brown  color.  The  lemon  and  orange 
yellow,  with  which  we  often  find  the  German  oval 
cakes  of  fancy  or  toilet  soaps  colored,  is  the  sulphide 
of  cadmium,  known  under  the  name  of  cadmium  }^el- 
low,  which  is  not  dissolved  in  the  soap,  but  merely 
suspended  by  very  careful  mixing,  for  it  is  rubbed  up 
with  oil,  and  added  to  the  soap  under  constant  stir- 
ring ; it  requires  but  a very  small  quantity  to  produce 
a lively  color,  and  neither  sun  nor  age  affect  the  color. 
The  cakes  or  tablets  are  formed  by  placing  a soft  mass 
of  soap  in  a mould  fixed  in  a lever  press  ; the  mould 
consists  of  a top  and  bottom  die,  fitting  into  a loose 
ring  ; by  a sudden  pressure  the  shapeless  mass  assumes 
the  form  of  the  ring,  and  is  embossed  on  the  top  and 
bottom. 

Naplks  Soap. 

This  highly  esteemed  shaving  soap,  always  imported 
from  Italy,  is  said  to  be  produced  by  saponifying  mut- 
ton suet  with  lime,  and  then  separating  the  fatty  acids 
from  the  soap  so  formed  by  means  of  a mineral  acid. 
These  fatty  acids  are  afterwards  combined  with  caustic 
potassa,  by  ebullition  in  the  usual  way. 

Transparent  Soaps. 

They  are  prepared  by  dissolving  well  dried  soaps 
in  alcohol.  Those  made  of  olive  oil  will  not  become 


PERFUMING  SOAPS. 


320 


transparent  with  alcohol,  but  become  opaque.  Good 
suet  and  rosin,  and  tallow  soaps,  are  best  suited  for  a 
transparent  soap.  Tlie  mode  of  proceeding  is  to  cut 
into  very  thin  ribbons,  by  means  of  a cutting  mill  or 
knife,  and  left  to  dry  in  the  air  or  sun  for  some  time, 
until  properly  diw ; it  is  then  pulverized,  and  then 
dissolved  in  strong  boiling  alcohol,  say  80  per  cent.; 
when  the  soap  is  liquid,  the  colors  and  perfumes  are 
added  to  it.  Three  and  a half  gallons  alcohol,  of  spec, 
grav.  0.849,  is  suitable  for  fifty  pounds  soap.  A still 
heated  by  steam  or  hot  water  is  generally  used  for  this 
purpose,  in  order  to  save  the  alcohol,  which  will 
amount  to  five  pints,  will  pass  over  from  the  employed 
three  and  a half  gallons  into  the  coolers  of  the  still. 
The  thick  liquid  in  the  still  is  turned  out  into  moulds 
arranged  for  them,  either  balls  or  square  moulds;  but 
their  capacity  should  be  one-third  larger  than  the  size 
of  the  forms  intended,  thus  allowing  for  the  shrinking 
of  the  soap  material.  The  soap  becomes  dry  after  a 
few  days,  and  when  of  a dull  appearance  is  turned  off 
with  a round  knife,  and  a neat  surface  produced  by 
rubbing  it  with  a fine  linen,  saturated  in  alcohol. 

Perfuming  Soaps. 

When  the  paste  or  soap  is  already  in  the  frames, 
the  process  of  perfuming  is  performed,  and  the  same 
must  be  nearly  cold,  else  the  essential  oils  would  be 
volatilized ; it  is,  therefore,  best  to  mix  the  colors  and 
perfumes  together  with  some  alcohol  or  glycerine,  and 
stir  them  well  up  in  the  paste.  In  France,  where  the 
finest  soaps  are  manufactured  in  the  cold  state,  very 
highly  perfumed  soaps  are  prepared.  Although  the 


330 


SOAP  MAKING. 


process  is  very  simple,  still,  their  mechanical  in- 
genuity makes  their  soaps  excelsior. 

Formulae  for  some  well  known  soaps  : 

Windsor  Soap. 

1.  (White.)  The  best  English  Windsor  soap  is  pro- 
duced from  a mixture  of 

1 pound  olive  oil, 

8 “ tallow, 

both  saponified  with  caustic  soda  lye,  and  scented  after 
the  removal  from  the  boiler.  Curd  soap,  well  scented, 
is  sold  generally  for  Windsor  soap,  being  flavored 
while  semi-liquid  with  oil  caraway,  and  a very  small 
quantity  of  oils  of  bergamot,  lavender  or  origanum 
are  added,  say  about  one  and  a half  pounds  of  the  oils 
to  everj^  hundred  weight. 

2.  Brown  AYindsor  soap.  It  is  the  same  as  the 
white,  only  colored  by  caromel,  and  sometimes  with 
umber  or  ochre. 


Honey  Soap. 

The  finest  rosin  soap,  colored  by  palm  oil,  or  palm 
oil  soap,  and  scented  with  rose  geranium  and  a little 
oil  of  bergamot  or  verbena.  Some  honey  soap  has  the 
following  composition  : 

1 pound  olive  oil  soap, 

1 “ palm  oil  soap, 

3 white  curd  soap, 

colored  by  a little  palm  oil  or  annatto,  and  scented 
with  various  fine  essential  oils  of  one  and  a half  pounds 
to  every  hundred  weight. 


AXMOND  SOAP. 


331 


Musk  Soap. 

The  base  of  this  soap  is  a good  suet  or  tallow  soap, 
scented  with  tincture  of  musk  and  a little  oils  berga- 
mot, cinnamon  and  cloves,  and  colored  by  caromel. 
Ambergris  soap  is  made  in  the  same  way  as  musk 
soap. 

Glycerine  Soap. 

Any  hard  soap  in  which  three  or  four  per  cent,  of 
glycerine  has  been  intimately  incorporated  while  in 
the  paste,  will  represent  this  soap.  It  is  colored  of  a 
red  or  rose  color,  or  orange-yellow;  oil  geranium  and 
oil  cassia,  with  a little  essential  oil  of  bitter  almonds, 
are  the  favorite  perfumes. 

Struve,  of  Leipsie,  prepares  a glycerine  soap  in  the 
following  manner.:  40  pounds  tallow,  40  pounds 

lard,  20  pounds  cocoaiint  oil,  are  saponified  with  45 
pounds  soda  lye  and  five  pounds  potash  lye,  of  40°  B., 
and  the  soap  is  to  be  made  in  the  cold  way.  To  the 
paste  are  then  added: 

G pounds  pure  glycerine, 
i ounce  oil  bergamot, 

1 “ Portugal, 

5 ounces  oil  bitter  almonds, 

3 vitiver. 

Almond  Soap. 

The  bitter  almond  soap  is  made  from  the  white 
curd  soap,  with  or  without  the  addition  of  1-7  of  its 
weight  of  olive  oil  soap,  scented  with  the  essential  oil 
of  almonds,  or  oil  of  mirbane,  in  the  proportion  of 


S32 


SOAP  MAKING. 


about  one  ounce  to  each  five  pounds  ; a little  oil  cassia 
improves  it. 


This  toilet  soap  is  the  white  curd  soap,  scented  with 
orris  root,  and  colored  with  litmus  tincture  ; also  by 
melting 

3 pounds  white  curd  soap, 

1 pound  olive  oil  soap, 

3 pounds  palm  oil  soap ; and  the  whole  scented 


Olive  soap,  2|-  pounds. 

White  curd  soap,  pounds. 

Oil  bergamot,  1 ounce. 

Oils  cassia,  cloves,  sassafras  and  thyme,  each  1-J 
drachms. 

Oil  neroli,  or  English  lavender,  1 drachm, 

Levigated  brown  ochre,  2 ounces. 

Another  bouquet  soap  is  made  from 

20  pounds  curd  soap, 
ounces  oil  bergamot. 

And  oils  cloves,  neroli,  sassafras  and  thyme,  ^ 
drachm. 

And  colored  with  2-|  ounces  brown  ochre. 


Violet  Soap. 


with  orris  root. 


Bouquet  Soap. 


Kose  Soap. 


Palm  oil  soap  in  shavings. 
White  curd  soap 
Soft  water, 


3 pounds. 
2 

4 ounces. 


MILITARY  SHAVING  SOAP. 


333 


Melt  in  a bright  copper  pan  and  water-bath,  and 
add  J ounce  of  vermilion,  or  perfume  with 

J ounce  otto  rose, 

1-J-  drachms  oil  bergamot, 

“ rose  geranium, 

f “ of  oils  cinnamon  and  cloves. 

Another  rose  soap  is  made  from  20  pounds  curd 
soap  and  the  variety  of  oils. 

Cinnamon  Soap. 

It  is  a mixture  of  tallow  and  oil  soap.  Take 

6 pounds  white  curd  soap, 

3J  “ palm  oil  soap, 

1 pound  cocoanut  oil, 
l-J  ounces  oil  cinnamon, 

J ounce  oils  bergamot  and  sassafras,  each, 

1 drachm  oil  English  lavender, 

J ‘‘  levigated  ochre. 

Lavender  Soap. 

It  is  Windsor  soap  scented  with  essential  oil  of 
lavender,  and  essence  of  musk  and  ambergris. 

Orange  Flower  Soap, 

Like  rose  soap,  flavored  with  oil  neroli,  and  ambergris, 
and  Portugal. 

Military  Shaving  Soap. 

To  the  white  olive  oil  soap  is  added  the  bayberry 
wax,  and  scented  with  oils  caraway  and  cassia. 

15* 


834 


80AJP  MAKING. 


Cream  Soap  and  Shaving  Paste. 

These  preparations  are  excellent  for  shaving 
are  composed  of 

White  soft  soap, 

Finest  honey  soap, 

Olive  oil, 

Water, 

Carbonate  soda, 


they 


4 ounces. 

2 ‘‘ 

1 “ 

2 tablespoonsful. 
1 drachm. 


Melt  them  together  and  form  a paste,  adding  a little 
])roof  spirit,  and  scent  at  will ; by  adding  about  1 
drachm  -spermaceti  the  paste  becomes  more  soft ; it 
makes  a lather  with  cold  water. 


Cream  Pearl  Soap. 

Take  lard  potash  soap,  or  white  soft  soap,  rub  it  up 
in  a marble  mortar,  so  as  to  become  a uniform  mass,  or 
pearly,  and  scent  it  with  oil  almonds  and  cassia. 

Shaving  Essence. 

Take  white  hard  soap,  J pound, 

“ pure  spirits,  1 pint, 

‘‘  water,  4 ounces, 

and  perfume  at  will.  Let  the  mixture  stand  in  a 
water-bath  for  a few  days,  occasionally  agitating  it, 
until  it  is  completely  dissolved ; draw  off  the  clear 
liquid,  and  perfume  it  to  suit. 

The  Commercial  Value  of  Soaps. 

Since  we  distinguish  soft  soaps  (potash  soaps)  from 
hard  soaps,  (soda  soaps,)  and  filled  soaps  from  grain 
soaps,  it  is  necessary  to  ascertain  the  intrinsic  value 
of  any  soap,  according  to  its  purity.  In  the  first 


COMMERCIAL  VALUE  OF  SOAPS. 


335 


place,  we  recognise  two  main  varieties,  or  groups  : first, 
the  rosin  soaps,  and  second,  the  fat  or  oil  soaps. 
Among  the  latter  are  the  more  important,  such  as 
tallow  soaps,  palm  oil,  cocoanut  and  olive  oil  soaps. 
In  addition  to  these,  however,  there  are  many  mixtures 
of  fatty  substances  in  combination  with  alkalies, 
known  as  soaps.  In  good  soaps  there  is  a definite 
proportion  between  the  water,  the  alkaline  'base,  and 
the  fatty  acids ; there  should  be  no  excess,  either  of  the 
base  or  of  the  constituents  of  the  fat,  at  the  same  time 
it  must  be  free  from  salt  or  an  excess  of  water,  which 
is  but  an  adulteration,  like  other  substances  known  to 
be  mixed  into  soaps,  like  sal  soda,  alum,  salt,  bone  ash, 
glauber  salt,  or  clay.  A good  soap  is  easily  soluble 
in  alcohol,  scarcely  leaving  one  per  cent,  of  solid  resi- 
due, and  forms  a gelatinous  liquid  in  boiling  water. 

A hard  soap  should  not  contain  more  than  25  per 
cent,  of  water,  of  rosin  not  more  than  40  per  cent., 
and  A)f  soft  soap,  not  more  than  52  per  cent.  For 
cocoanut  oil  soaps,  a larger  amount  of  water  than  52 
per  cent,  may  be  allowed.  In  the  yellow  soap,  a part 
of  the  fat  is  replaced  correctly  by  10  to  15  per  cent, 
of  rosin.  All  these  proportions  are  reliable,  and  if 
increased  or  replaced  by  other  substances,  the  quality 
of  the  soap  is  diminished,  although  some  soap  makers 
think  that  an  excess  of  alkali  is  quite  justifiable,  in 
order  to  make  the  soap  more  soluble ; they  do  not  con- 
sider that  the  various  salts  contained  in  many  waters 
form  insoluble  compounds  with  the  fatty  acids  of  the 
soap,  while  an  excess  of  some  sal  soda  would  be  more 
advantageous.  The  composition  of  the  different 
kinds  of  soap,  by  various  manufacturers,  are  given  in 
the  following  tables  : 


HARD  SOAPS. 


336 


SOAP  MAKING 


tH  ^ tH 

05  . i>;  ,05  , , rij  i>  00  , 05  W (M,  , . 

'^'ooooOTHrHoiio  c6-riH05odcoooT-4iooo 

Oi  1-i  Oi  a CO  lO  no  lO  T-l  (M  CO  <M  <M  <M  rf  CO  r-l 


•0TipT98J 
0iqnfosur 
puB  0iui'i 


(•10  ‘^M) 
•itlBS 


'bssb;o  j iCao; 


•Bpos  ^xa 


OO'^  GO 
' GO  05  05 


GO  05 

i>  O , <0i  . CQ  1C  O? 

i>£>ici>05idido5 


O?  1C 

00  Oi  GO  CO 

CO  05 


•UTS 

■oa  pat? 


! , , . ci  , 1C 

' IC  'TjH  CD  cd  03 
' J>  CO  CO  1C  CO  CO  CO 


•sppvA^M 


1C  CO  1—1 

C<* 

THcdoici>o6cdo'^ic 

OOi>lC'^COCDCOlCCDi> 


o 

m 

m 

v» 

a 

§ f 

> 

'O  ^ p.  o 

o 

fl  "o  p 02 

gl^  g® 

C ;h  c3 

0)  +=  o bb 

<1  W<JQ 


o 


. ® 

. “1 
. oS 

• o 

: ^ 

• a 

• o 02 

• S *^.2 
: S ^ s 

• « t/2 

• Ph+3  o' 

pH 


d . 
o • 

^ QQ  P 0)  O 

° ^ -P 

hr 

^«2  cpH  d fl  ^ 
’ hi  W "d  © 

ss  a §.-s 

m 

m 

<o 

" 3 

© • 
2 ' 

go 

d 

o 

P^-S 

§02  O 

02rd  ^ 

•p  3 ^ 

rP  © 


I 


3 

& 


♦ 10.6  Kosin  and  22  Fatty  Acids. 


HARD  ^OkVB— Continued. 


TALUEMETET  OF  SOAPS, 


337 


^ AO  cq  , _ lo 
j>  oo  CO  cd  w JO 

tH  05  CO  CO  'sJH  £- 

•QTipiSgj 
9tqnpsat 
puB  amini 

(•TO 

"BSSB^OJ  jfjQ 

•Bpos  ^ja 

, lO  05  . »o  .. 

i>  cd  cd  i>  CD  TfH 

*UIS 

-OJI  puB  :;bj 

• o • • • • 

. t-  • . . . 

•spiov 

«d  • O cd  05  05 
i>  • O lO  to  C5 

Name. 

Poppy  Oil  Soap, 

Glasgow  Brown  Resin  Soap,  

Glasgow  White  Soap, 

Manchester  Palm  Oil  Soap, 

London  Curd  Soap, 

London  Marine  Soap, 

338 


SOAP  MAKINO. 


To  Determine  the  Amount  of  Water  op  a Com- 
mercial Soap. 

Take  80  grains  of  the  respective  soaps,  and  put  them 
in  a water-bath,  and  add  a saturated  solution  of  nitre, 
and  heat  both  to  the  boiling  point ; keep  boiling  for 
two  to  three  hours,  and  add  more  water,  if  some 
should  be  evaporated  during  the  boiling ; note  the 
weight,  and  keep  for  two  hours  more  heated  ; if  not 
diminished  after  that  time,  it  proves  that  all  the  water 
is  expelled.  If  the  original  weight  of  the  soap  was 
80  grains,  and  after  drying  was  but  67  grains,  it  would 
make  it  equal  to  16J  per  cent. 

To  Determine  the  Amount^  of  Fat. 

By  decomposing  the  soap  by  an  acid,  the  fat  is 
easily  found.  By  putting  80  grains  in  a porcelain 
dish,  and  adding  20  to  30  times  as  much  in  weight  of 
oil  of  vitriol,  diluted  12  times  with  water,  and  heating 
the  whole  over  a lamp,  until  the  fat  is  floating  on  the 
top.  If  60  grains  remain,  deduct  for  tallow,  which 
is  equal  to  88.05  grains,  and  80  grains  soap  would 
contain  72.8  per  cent. 

Rosin  is  detected  by  ascertaining  the  weight  left 
undissolved  after  the  alcohol  has  taken  up  all  the  fat, 
which  is,  however,  a very  uncertain  test.  Other  pro- 
cesses have  been  proposed,  by  means  of  strong  hydro- 
chloric acid,  which  appears  to  be  more  reliable. 

Free  alkali  may  be  easily  ascertained  if  it  exists  in 
soap. 

The  following  substances  are  used  for  Ailing  up  the 


FILLING  UP  THE  SOAP. 


339 


soap,  some  of  wJiich  may  be  advantageously  employed, 
and  some  serve  as  adulterations  : 


Gboup  I. 

Group  II. 

Group  III. 

Water. 

Earthy  Matters  and  Salts, 

Organic  Matters. 

Soluble  and  Insoluble  in  Water. 

Soluble  and  Insolu- 
ble in  Water. 

Soluble. 

Chloride  of  Sodium. 
Soda. 

Glauber  Salt. 

Borax. 

Soluble  Glass. 
Carbonate  of  Ammonia 
Alum. 

Acetate  of  Lead. 

Insoluble. 

Soluble  in  Hydrochlo- 
ric Acid, 
MAGNESfA. 

LIME. 

CHALK. 

BONE  ASHES. 

PIPE  CLAY. 

Soluble. 

Sugar. 
Starch. t 
Dextrin. 
Glue. 

Insoluble. 

Free  Rosin. 
Free  Fat.  ' 

Hot  Soluble  in  Hydro- 
chloric Acid. 
SULPHATE  OP  BA- 
RYTES. 

SAND.* 

The  object  of  the  introduction  of  soluble  glass  in  the 
manufacture  of  soap,  or  as  a substitute,  if  economy  is 
at  stake,  may  be  exemplified  by  the  following  remarks  : 
The  treatment  of  lyes  alone,  with  wool  or  silk,  prove 
the  superiority  of  the  soluble  glass,  as  it  removes  but 
externally  the  adhering  dirt,  wdthout  any  injurious 
effect.  The  slippery  and  adhesive  consistency  of  solu- 
ble glass  act  likewise  beneficial  in  the  easy  w^ashings, 
and  rinsings  with  much  water  the  adhering  impurities. 
There  are  many  advantages  in  its  applications  on 


* An  admixture  of  sand  cannot  be  regarded  as  fraud,  if  the  soap 
is  sold  as  sand  soap. 

f We  do  not  know  if  starch  has  any  cleansing  qualities  ; it  is  so 
stated  in  a report  on  the  different  uses  of  the  potato,  published  in 
1827  by  the  two  French  chemists,  Payen  and  Chevalier,  but  we 
doubt  it. 


340 


SOAP  MAKING. 


wool,  silk,  cotton  and  leather  ; it  is  stronger  than  com- 
mon soap,  requires  a less  quantity,  and  either  hard, 
soft,  cold  or  lukewarm  w^ater  may  be  employed. 

The  labor  and  saving  of  fuel  is  an  advantageous 
economy  ; it  preserves  also  many  colors,  which  are 
not  fast,  much  better  than  common  soap ; it  resists,  in 
fact,  almost  all  colors.  From  one  to  four  pounds 
liquid  glass  is  sufficient  for  100  pounds  of  water.  As 
that  used  for  wool  is  quite  sufficient  for  a menstruum, 
it  is  employed  quite  extensively  in  Europe  for  wash- 
ing and  fulling  of  wool,  and  it  has  been  used  long 
before  the  soluble  glass  was  known,  by  dissolving 
flints  in  caustic  lye  prepared  from  wood  ashes. 

The  Prussian  Government  has  found  it  advisable 
for  the  introduction  of  the  soluble  glass  in  the  military 
and  other  royal  institutions  and  prisons,  and  also  for 
the  paper  manufacturers,  and  their  extensive  linen 
establishments  ; and  instituted  experiments  as  to  the 
practicability  of  a general  economical  application. 

In  the  cotton  mills  it  has  proved  a saving  of  fifty 
per  cent,  by  substituting  it  for  starch  and  flour,  which 
was  so  indispensable  for  fastening  the  colors;  and  in 
England,  thousands  of  pounds  sterling  have  been 
economized  by  its  application.  In  our  late  war  the 
consumption  of  the  soluble  glass  in  that  branch  of 
industry  of  the  United  States  was  very  extensive. 
The  soap  manufacturer,  who  formerlj^  did  use  rosin 
for  an  adulteration  or  admixtui'e,  the  cost  of  which 
was  formerly  but  two  dollars,  but  rose  to  twenty-five 
and  thirty  dollars  per  barrel  of  180  pounds,  was 
obliged  to  resort  to  the  use  of  soluble  glass  in  its 
various  forms,  either  as  liquid  or  jelly. 

Posin  is  now  again  more  employed  than  the  soluble 


CETOLITE  SOAP. 


341 


glass  ; not,  however,  for  the  reason  that  it  is  better  as 
a sophisticator,  but  because  the  soap  maker  has  an 
idea  4hat  the  soap  formed  from  rosin  with  fat  suited 
better,  and  is  more  time  saving.  He  does  not  consider 
all  the  circumstances  ; such  as  the  smell  and  touch 
produced  in  the  handling  or  washing  with  rosin  soap, 
and  that  the  admixture  of  soluble  glass  is  no  adultera- 
tion, but  an  improvement,  and  that  it  is  as  economical 
as  rosin  soap. 

The  Cryolite  Soap, 

which  was  introduced  in  the  market,  is  a rosin  soap, 
to  which  the  powdered  cryolite  is  added  by  crutching, 
or  it  is  added  right  after  the  saponification  has  taken 
place,  before  it  is  taken  out  from  the  kettle.  The 
writer  has  seen  such  a soap,  which  was  quite  soft,  and 
could  not  be  made  hard,  except  by  adding  some 
adujteration,  such  as  clay  or  talc,  if  it  is  intended  to 
be  a saleable  soap. 


I isrj)  E X 


PAGE 


Action  of  Acids, 278 

Action  cf  Alkalies, 278 

Action  of  Hydrofluoric  Acid,..  278 

Adhesive  Lubricator, 164 

Albumen  liable  to  decomposi- 
tion,   131 

Alkaline  Sidts  from  Hydraulic 

Lime, 112 

Alkalies  in  the  Soluble  Glass,.  36 

Alkalies— Soap, • 292 

Almond  Soap, 331 

Alumina,  an  undesirable  ingre- 
dient in  Glass, 216 

American  Hydraulic  Mortar. . . 96 

Amorphous  Glass, 281 

Amulets,  Glass, 284 

Analysis  of  Sap, 136 

Ancient  Mortars, 100 

Animal  Fats, 305 

Annexing  of  Pots,..* 213 

Annealing  Oven 209 

Apothecaries’  Vials, 234 

Apparatus  in  Soap  Making,.. . . 291 
Application  of  Soluble  Glass  in 

Brooklyn  Navy  Yard, 15 

Aquamarine  and  Garnet, 269 

Aquarium  Cement, 165 

Areometric  degree  of  Lye, 298 

Arsenic, 36 

Arsenic  promotes  decomposi- 
tion,   217 

Artificial  Grindstones, 196 

Artificial  Meerschaum, 60 

Artificial  Stone,  general  ideas 

on,.’ 94 

Artificial  Stone,  report  on, 178 

Art  of  Manufacturing  Glass,. . . 290 

Astronomy  through 'Glass, 282 

Avanturin  Glass, 273 

Barrel  Protection, 163 

Baryta  and  Zinc  Paint, 115 

Baryia  used  in  Glass, 216 

Beef  Tallow, 305 

Beton  Coiguet, 150 


PAGE 


Beton’s  Crushing  Weight, 186 

Beton’s  Keport, 181 

Bible  refers  to  Glass, 283 

Black  Ash, 293 

Blanc  Fix  Manufacture, 123 

Blowing  of  Glass 283 

Bohemian  Crystal, 235 

Bone  Ashes, 217 

Bone  Fat, 306 

Boracic  Acid, 312 

Borax  and  Boracic  Acid, 217 

Bouilly’s  Cements, 76 

Bouquet  Soap, 332 

Brown  and  Miller  Pavement,. . 153 

Brown  Windsor  Soap 330 

Butter,  its  melting  point, 3u6 

CarbolicAcid  precipitates  Silica,  127 

Carbonate  of  Soda, 294 

Castile  Soap, 319 

Cast  Iron  Kettles, 291 

Causes  of  Hardening  of  Glass, . 109 

Cements,  Lecture  on, 71 

Cement  of  Manganese,  &c.,.. , 121 

Chalk  converted  in  Silica 113 

Cheapest  White  and  Yellow 

Glass 165 

Chemical  Properties  of  Glass,..  277 

Chinese  Water  Proof, 177 

Chloride  Calcium, 17,  193 

Cinnamon  Soap, 333 

Circular  on  Uses  of  Soluble 

Glass, 47 

Cistern  Cement, 171 

Cistern  Lining 105 

Cocoauut  Oil, 301 

Cocoanut  Oil  Soap, 318 

Colored  Cements, 173 

Comforts  of  Glass, 282 

Commercial  Value  of  Soap, 334 

Common  Flint  Glass,  254 

Common  Mortar, 77 

Component  Pots, 265 

Composition  of  Glass,.  .206,  212,  288 
Consumption  of  Coal, 203 


344 


INDEX. 


PAGE 


Contents  of  Pots, 256 

Cracks  in  Stone, 170 

Cream  Pearl  Soap, 334 

Cream  Soap  and  Shaving  Paste,  334 

Creosote  on  Woody  Fibre, 127 

Crown  and  Plate  Glass  Fur- 
nace,  209 

Crown  Glass, 236 

Crucibles  or  Pots, 211 

Cryolite  Glass, 276 

Cryolite  Soap, 341 

Crystal  Glass, 252 

Gullet  Waste  Glass, 218 

Damp  Cellars, 81 

Date  of  Glass  Making 283 

Decay  of  Wood,, 130 

De-Coloring  Materials, 218 

Definition  of  Glass, 283 

De  Milly  Process, 311 

Deville’s  Remarks, 70 

Discovery  of  Glass, 282 

Doebereiner’s  Method, 15 

Double  Soluble  Glass 39 

Drain  and  Gas  Pipe  Cement,. . 170 

Easel  Painting, 122 

Effect  of  Acids  on  Glass, 277 

Effect  of  Air  on  Glass, 277 

Effect  of  Water  on  Glass, 277 

Elaidic  Acid, 307 

Elastic  Glass, * 281 

Electric  Soap, 316 

English  Bottle  Glass, 228 

English  Crown  Glass., 238 

Eremacausis, 131 

Etching  on  Glass, 259 

Extent  of  Infusorial  Deposits,.  19 

Family  Soap  manufacture, 315 

Faraday’s  Glass, 263 

Faults  in  Glass, 224 

Felspar  a good  body, 217 

Felspar  as  constituent, 220 

Figging  Soap, 326 

Filling  Materials  in  Soap, 339 

Filling  of  Soap, 293 

Finingof  Glass, 223 

Fire  and  Water  Proof  Cement,  94 

Fire  Clay, 211 

Fish  Oil, 306 

Fiske  Concrete  Pavement, 155 

Flashing  and  Casing, 271 

Flint  Glass, 252 

Flint  Glass  Furnace, 207 

Fluorspar, 36 

Fluorspar  much  in  use, 217 


PAGE 


Fluxes, 275 

Formula  for  Silica  Soap, 323 

Formula  for  Tallow  Soap, 318 

Fremy’s  Remarks  on  Cement, . . 68 

Ph  ench  Bottle  Glass, 229 

French  Flint  Glass, 256 

PTencli  Plate  Gla'S, 242 

Fuel  in  Glass  Making, 221 

Furnaces,  duration  of, 208 

Gas  Pipe  Cement, 172 

General  Protection, 162 

General  Remarks  on  Soluble 

Glass 199 

General  Rules  for  Wood  Pave- 
ment,'  159 

German  Hydraulic  Cement,...  100 

Glass  Harmonicon,, 282 

Glass  Makers’  Soap, 219 

Glass  Making  Art, 205 

Glass  Materials, 214 

Glass  Mosaic, 272 

Glass  Painting, 273 

Glazing  and  Enameling, 167 

Glory  Hole, HO 

Glue  Substitute, 167 

Glycerine, 289 

Glycerine  Soap, ; 331 

Granite  Pavement, 153 

Grape  Vine  Manure, 166 

Gravel  Cement, 172 

Green  Bottle  Glass, 228 

Green  Sand, 200 

Green  Sand  a substitute  for 

Sand, 217 

Grinding  and  Polishing  Glass, . 246 

Guinaud’s  Plan, 263 

Gypsum  Cement, 170 

Hard  and  Soft  Soaps,, 289 

Hardening  Mortar, 277 

Hardening  Process  of  Cement,  98 

Hard  Soaps, 315 

Herculaneum  Glass, 284 


History  of  Roman  Cement, ....  109 

Hock  Wine  Bottles, 231 

Hogs’  Lard, 306 

Honey  Soap, 330 

Horse  Fat, 306 

Hubert’s  Apparatus, 292 

Hydraulic  Lime, 62 

Hydrofluoric  Acid, 260 

HydrofluoricAcid  hardens  Gyp- 
sum  ^ 120 

Hydrofluoric  Acid  hardens  the 
Lime, H9 


INDEX. 


345 


PAGE 

Hydrofluoric  Acid  heightens 
the  colors, 113 

Imperfect  Conduction  of  Glass,  279 
Impregnation  of  Wood  by  pres- 
sure,  132 

Impurities  of  Palm  Oil., 302 

Iron  an  unwelcome  element  in 

Glass, 217 

Iron  Block  Pavement, 154 

Iron  Cements, 75,  171 

Iron  Ship  Bottoms  preserved,.  164 


PAGE 


Mottled  Soap,. 324 

Musk  Soap, 331 

Mutton  Suet, 305 

Naples  Soap, 328 

Nature  of  Limestones, 65 

New  Soap, 316 

Nicholson  Pavement, 146 

Nicholson’s  Process, 156 

Nigger, 315 

Nitrate  of  Soda, 36 


Nitrate  of  Soda  Formation, ....  Ill 


Kaulbach’s  Soluble  Glass, 40 

Kneading  of  Glass, 211 

Krieg’s  Carbolic  Application,..  127 

Kuhirnann’s  Process, 17 

Kyanizing, 129 

Lard  Oil, 306 

Lavender  Soap, 333 

Lead,  the  ingredient  in  Crystal 

Glass, 216 

Le  Blane’s  Discovery, 215 

Lemon  Yellow  Soap, 333 

Liebig’s  Infusorial  Process, ....  39 

Liebig’s  Method, 16 

Lime  the  constituent  of  Glass, . 216 
Lime  and  organic  substances 

treated,, 125 

Looking-Glass  Tarnish, 278 

Lumber  Drying 140 

Lye,  its  meaning, 296 

Manganese  and  Zinc  Cement,. . 101 
Manufacture  of  Soluble  Glass,.  13 

Margaric  Acid, , 288 

Marseilles  Experiments  with 

Beton, 187 

Marseilles  Soap  Manufacture,. . 290 
McCully  & Co.,  Green  Glass 

Manufacturers, 286 

McGonegal  Pavement, 157 

Melting  of  Materials, 222 

Merits  of  Wooden  Pavements,.  149 

Metallic  Cement, 176 

Method  of  Preserving  Wood, . . 141 

Microscope  through  Glass, 282 

Military  Shaving  Soap, 333 

Mixing  Apparatus, 221 

Mode  and  Mechanical  Opera- 
tion,   257 

Mode  of  Application  of  Wood 

Pavement, 126 

Mofurra  Tallow, 304 

Mortar, 62 

Mortar  Composition, 77 


Oil  Mirbane, 317 

Oil  of  Poppy, 304 

Oleic  Acid, 288,307 

Olive  Oil, 304 

Optical  Glass, 261 

Orange  Flower  Soap, 333 

Origin  of  Glass, 18 

Outside  Wall  Cement, 174 

Painting  on  Metals, 121 

Painting  on  Stone, 116 

Painting  on  Wood, 119 

Palmitin 300 

Palm  Oil, 301 

Palm  Oil  Bleaching, 304 

Palm  Oil  Soaps, 321 

Parisian  System  of  Pavements,  147 
Payen’s  Kecommendation, ....  132 

Pearl  Ash, 36 

Peasley  Cement, 171 

Pennsylvania  Glass  Manufacto- 
ries,  285 

Per  Centage  of  Phenic  Acid  in 

Coals, 142 

Perfuming  of  Soaps, 329 

Permanent  White, 123 

Peroxide  of  Manganese  in 

Glass, 219 

Petitjean’s  Method, 250 

Phenic  Acid,  the  Preservative, . 142 
Physical  Characters  of  Glass,. . 279 
Piers  and  Breakwater  Beton,. . 187 
Pittsburgh  Glass  Manufacture,  286 

Plate  Glass, 241 

Pliny’s  Remarks, 139 


Portland  Cement  Analysis, 71 

Portland  Cement  Capacity, ....  71 

Portland  Cement  Manufacture,.  83 
Portland  Cement  Production. . 84 

Portland  Cement  Tensile 


Strength, 87 

Portland  Vase, 283 

Potash  Soluble  Glass, 37 

Potassa  and  Soda, 292 


INDEX. 


846 


PAGE 


Preserration  of  Old  Monu- 
ments,   95 

Preservation  of  Wood, 129 

Preserving  Walls, 161 

Properties  of  Palm  Oil, Sol 

Quartz,  its  characters,. 23 

Quartz,  its  forms, 22 

Quartz,  its  Mineralogical  Cha- 
racters,  26 

Quartz,  its  Varieties, 23 

Eail-Road  Sleepers, 126 

Eansome’s  Method, 50 

Eansome’s  Stone  Eeport, 189 

Eeaumur’s  Glass 207 

Eed  Ink  from  Silica, 122 

Eed  Oil  Soap, 308 

Eesistance  to  Water  and  Ileat,.  lOl 

Eoadway  Pavements, 152 

Eobbins’  Pavement 158 

Eobbins’  Pretended  Discovery,  144 
Eoberts’ latest  Preservative,...  l74 

Eoman  Cement, 72 

Eondout  Cement  Analysis, 73 

Eoofing  Shingles, 126 

Eoof  Shingles  Preservative,.. . 145 

Eosedale  Eiver  Cement, 97 

Eose  Soap, 332 

Eosin  Detection, 338 

Eupert’s  Drops, 280 

Sal  Soda, 293 

Saltpetre  Formation, 110 

Saltpetre  Percentage, Ill 

Sandiver  or  Glass  Gall, 223 

Sapphire  and  Amethyst, 269 

Seeley's  Concrete, 159 

Setting  of  Pots, 213 

Shaving  Essence 334 

Ship  an  I other  Timber, 126 

Siemen’s  Apparatus, 42 

Siemen’s  Directions, 45 

Silica, ; 21 

Silica  Soaps, 321 

Silicification  of  Chalk, 53 

Silicification  of  Organic  and  In- 
organic Substances, 113 

Silicification  of  Wood, 124 

Silicium, 20 

Silvering  Fluid  for  Glass, 249 

Smalt, 219 

Soap  Making, 288 

Soda, 36 

Soda  Soluble  Glass, 38 

Soda  Water  and  Champaign 
Bottles, 230 


1>A0B 

Soft  Soaps,  320 

Soluble  Glass, 13,  276 

Soluble  Glass  fi>r  Silk 340 

Soluble  Glass  lor  Wool, 340 

Soluble  Glass  in  Prussia, 340 

Soluble  Glass,  its  various  appli- 
cations,   60 

Soluble  Glass  Soap, 322 

Sources  of  Sand, 215 

Sorel’s  Cement, 107 

Specific  Gravity  of  Glass, 287 

Sperm  Oil, 3u7 

Squaring  Glass, 247 

Stafford  Pavement, 146 

Stafford’s  Process, 159 

Steam  Eesisting  Cement, 169 

Stearic  Acid., 288 

Stereochromic  Painting, 116 

Stillingia  Butters, 304 

Stone  Cement, 173 

Stone  Pavement, 157 

Strass  and  Colored  Glass, 264 

Street  Pavements, 145 

Strength  of  Alkali, 294 

Strength  of  Lye, 297 

Struve’s  Glycerine  Soap, 331 

Sulphate  of  Soda, 36 

Sulphuric  Acid  Saponification,  313 

Superheated  Steam, 291 

Superstition  of  Glass 184 

Sweetening  Cistern  Water, 171 

Table  for  Lyes, 297 

Tables  of  Amount  of  Water  in 

newly  filled  Woods, 139 

Tablet  Soaps, 328 

Tallow  Chandler, 290 

Tallow  Soaps, 326 

Tail’s  Cement, 166 

Test  for  Soaps, 338 

The  Battledore, 225 

The  Cold  Covering, 224 

The  Division  of  Glass, 226 

The  Frit, 221 

The  Glass  House, 207 

The  Glass  Maker’s  Chair, 225 

The  Hot  Covering, 224 

The  latest  Classification, 227 

The  Marver, 225 

The  most  Eefractory  Cement,. . 177 

The  Pontel  or  Pontj', 225 

The  Pucellas, 215 

The  Shears, 225 

The  Springtool, 225 

Timber  Kot, 135 

Toilet  Soaps, 325 

Topaz,  Euby  and  Emerald, ....  268 


INDEX. 


84:7 


PAGE 

Transparent  Balls, 329 

Transparent  Cakes, 629 

Transparent  Soap, 828 

United  States  Glass, 285 

Varieties  of  Glass, 13 

Varieties  of  Soluble  Glass,. ....  14 

Various  Cements, 168 

Vegetable  Fats, 301 

Venetian  Filagree, 272 

Venetian  Skill...... 284 

Vicat’s  Keniarks, 117 

Victoria  Stone, 176 

Violet  Soap, 332 

"Wagner’s  Eemarks  on  Soluble 

Glass, 55 

Wagner’s  Varieties  of  Soluble 
Glass, 55 


PAGE 

Wall  Damp 'Cement, 79 

Weight  of  Lye, 299 

White  Ash, 293 

White  Bottle  Glass, 233 

White  Windsor  Soap, 330 

William  Frice,  the  Glass  Paint- 
er,   285 

Window  Glass, 236 

Windsor  Soap, 330 

Wooden  Blocks, 126 

Wooden  Roof  Shingles, . .....  128 
Working  Tools  in  Glass  House,  225 

Yellow,  Blue  and  Green  Glass,  267 

Zeolites,  Natural  Silicates, 112 

Zinc  Cement, 169 

Zinc  Glass, 263 


/ 


Date  Due 


‘c.v  V ' 

»r 

' ri 

i: 

.y 

L.  B.  CAT.  NO.  1137 

F43  6- 

^ b~  & 4^ 

. LL_-  f.  /) 

^ ^ ^ /-  y j"  j" 


GETTY  CENTER  LIBRARY 


